Exhibit 5.1

Our ref DLK/742877-000006/30796523v3

Canaan Inc.

28 Ayer Rajah Crescent

#06-08

Singapore 139959

22 November 2024

Canaan Inc.

We have acted as Cayman Islands legal advisers to Canaan Inc. (the "Company") in connection with the Company’s registration statement on Form F-3, including all amendments or supplements thereto (the "Registration Statement"), initially filed with the Securities and Exchange Commission (the “Commission”) on 17 April 2024 under the U.S. Securities Act of 1933, as amended, and the prospectus supplement dated 22 November 2024 (the “Prospectus Supplement”) relating to the sale of the Company's series A-1 convertible preferred shares of par value US$0.00000005 each (the "Series A-1 Preferred Shares"), convertible into American depositary shares (the "ADSs") representing the Company's class A ordinary shares of par value US$0.00000005 each (the "Class A Ordinary Shares" and, together with the Series A-1 Preferred Shares, the "Shares") by the Company in accordance with a Securities Purchase Agreement dated 19 November 2024 (the “Securities Purchase Agreement") entered into by and among the Company and the Buyers as named therein.

We are furnishing this opinion and consent as Exhibits 5.1 and 23.2 to the Registration Statement.

1 Documents Reviewed

For the purposes of this opinion, we have reviewed only originals, copies or final drafts of the following documents:

1.1 The certificate of incorporation of the Company dated 6 February 2018 and the certificate of incorporation on change of name of the Company dated 24 April 2018 issued by the Registrar of Companies in the Cayman Islands.

1.2 The amended and restated memorandum and articles of association of the Company as adopted by a special resolution passed on 4 October 2019 and effective immediately prior to the completion of the Company’s initial public offering of the ADSs representing the Shares (the "Memorandum and Articles").

1.3 The written resolutions of the board of directors of the Company dated 13 November 2024 (the "Board Resolutions").

1.4 A certificate from a director of the Company, a copy of which is attached hereto (the "Director's Certificate").

1.5 A certificate of good standing dated 18 November 2024, issued by the Registrar of Companies in the Cayman Islands (the "Certificate of Good Standing").

1.6 The Registration Statement.

1.7 The Prospectus Supplement.

1.8 The Securities Purchase Agreement.

2 Assumptions

The following opinions are given only as to, and based on, circumstances and matters of fact existing and known to us on the date of this opinion letter. These opinions only relate to the laws of the Cayman Islands which are in force on the date of this opinion letter. In giving these opinions we have relied (without further verification) upon the completeness and accuracy, as of the date of this opinion letter, of the Director's Certificate and the Certificate of Good Standing. We have also relied upon the following assumptions, which we have not independently verified:

2.1 Copies of documents, conformed copies or drafts of documents provided to us are true and complete copies of, or in the final forms of, the originals.

2.2 All signatures, initials and seals are genuine.

2.3 There is nothing contained in the minute book or corporate records of the Company (which we have not inspected) which would or might affect the opinions set out below.

2.4 There is no contractual or other prohibition or restriction (other than as arising under Cayman Islands law) binding on the Company prohibiting or restricting it from entering into and performing its obligations under the Registration Statement and the Securities Purchase Agreement.

2.5 The Company will have sufficient authorised capital to effect the issue of the Shares at the time of issuance.

2.6 The Securities Purchase Agreement is, or will be, legal, valid, binding and enforceable against all relevant parties in accordance with their terms under all relevant laws (other than, with respect to the Company, the laws of the Cayman Islands).

2.7 The choice of the laws of the Cayman Islands as the governing law of the Securities Purchase Agreement has been made in good faith.

2.8 The capacity, power, authority and legal right of all parties under all relevant laws and regulations (other than, with respect to the Company, the laws and regulations of the Cayman Islands) to enter into, execute, unconditionally deliver and perform their respective obligations under the Securities Purchase Agreement.

2.9 No monies paid to or for the account of the Company in respect of the Shares represent or will represent proceeds of criminal conduct or criminal property or terrorist property (as defined in the Proceeds of Crime Act (As Revised) and the Terrorism Act (As Revised) respectively).

2.10 There is nothing under any law (other than the law of the Cayman Islands), which would or might affect the opinions set out below.

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3 Opinion

Based upon the foregoing and subject to the qualifications set out below and having regard to such legal considerations as we deem relevant, we are of the opinion that:

3.1 The Company has been duly incorporated as an exempted company with limited liability and is validly existing and in good standing with the Registrar of Companies under the laws of the Cayman Islands.

3.2 The authorised share capital of the Company is US$50,000 divided into 1,000,000,000,000 shares of par value US$0.00000005 comprising of (i) 999,643,050,556 Class A Ordinary Shares of a par value of US$0.00000005 each, (ii) 356,624,444 Class B Ordinary Shares of a par value of US$0.00000005 each, (iii) 125,000 series A preferred shares of a par value of US$0.00000005 each, and (iv) 200,000 Series A-1 Preferred Shares.

3.3 The issue and allotment of the Shares have been duly authorised and when allotted, issued and paid for as contemplated in the Registration Statement, the Prospectus Supplement and the Securities Purchase Agreement, the Shares will be legally issued and allotted, fully paid and non-assessable. As a matter of Cayman law, a share is only issued when it has been entered in the register of members (shareholders).

3.4 The statements under the caption "Taxation" in the Prospectus Supplement forming part of the Registration Statement, to the extent that they constitute statements of Cayman Islands law, are accurate in all material respects and that such statements constitute our opinion.

4 Qualifications

4.1 To maintain the Company in good standing under the laws of the Cayman Islands, annual filing fees must be paid and returns made to the Registrar of Companies within the time frame prescribed by law.

4.2 The obligations assumed by the Company under the Securities Purchase Agreement will not necessarily be enforceable in all circumstances in accordance with their terms. In particular:

(a) enforcement may be limited by bankruptcy, insolvency, liquidation, reorganisation, readjustment of debts or moratorium or other laws of general application relating to, protecting or affecting the rights of creditors and/or contributories;

(b) enforcement may be limited by general principles of equity. For example, equitable remedies such as specific performance may not be available, inter alia, where damages are considered to be an adequate remedy;

(c) some claims may become barred under relevant statutes of limitation or may be or become subject to defences of set off, counterclaim, estoppel and similar defences;

(d) where obligations are to be performed in a jurisdiction outside the Cayman Islands, they may not be enforceable in the Cayman Islands to the extent that performance would be illegal under the laws of that jurisdiction;

(e) the courts of the Cayman Islands have jurisdiction to give judgment in the currency of the relevant obligation and statutory rates of interest payable upon judgments will vary according to the currency of the judgment. If the Company becomes insolvent and is made subject to a liquidation proceeding, the courts of the Cayman Islands will require all debts to be proved in a common currency, which is likely to be the "functional currency" of the Company determined in accordance with applicable accounting principles. Currency indemnity provisions have not been tested, so far as we are aware, in the courts of the Cayman Islands;

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(f) arrangements that constitute penalties will not be enforceable;

(g) enforcement may be prevented by reason of fraud, coercion, duress, undue influence, misrepresentation, public policy or mistake or limited by the doctrine of frustration of contracts;

(h) provisions imposing confidentiality obligations may be overridden by compulsion of applicable law or the requirements of legal and/or regulatory process;

(i) the courts of the Cayman Islands may decline to exercise jurisdiction in relation to substantive proceedings brought under or in relation to the Securities Purchase Agreement in matters where they determine that such proceedings may be tried in a more appropriate forum;

(j) we reserve our opinion as to the enforceability of the relevant provisions of the Securities Purchase Agreement to the extent that they purport to grant exclusive jurisdiction as there may be circumstances in which the courts of the Cayman Islands would accept jurisdiction notwithstanding such provisions;

(k) any provision in the Securities Purchase Agreement which is governed by Cayman Islands law purporting to impose obligations on a person who is not a party to the Transaction Document (a "third party") is unenforceable against that third party. Any provision in the Transaction Document which is governed by Cayman Islands law purporting to grant rights to a third party is unenforceable by that third party, except to the extent that the Transaction Document expressly provides that the third party may, in its own right, enforce such rights (subject to and in accordance with the Contracts (Rights of Third Parties) Act (As Revised) of the Cayman Islands);

(l) any provision of the Securities Purchase Agreement which is governed by Cayman Islands law which expresses any matter to be determined by future agreement may be void or unenforceable;

(m) a company cannot, by agreement or in its articles of association, restrict the exercise of a statutory power and there is doubt as to the enforceability of any provision in the Securities Purchase Agreement whereby the Company covenants to restrict the exercise of powers specifically given to it under the Companies Act (As Revised) (the "Companies Act"), including, without limitation, the power to increase its authorised share capital, amend its memorandum and articles of association or present a petition to a Cayman Islands court for an order to wind up the Company; and

(n) enforcement or performance of any provision in the Securities Purchase Agreement which relates, directly or indirectly, to an interest in the Company constituting shares, voting rights or ultimate effective control over management in the Company may be prohibited or restricted if any such relevant interest is or becomes subject to a restrictions notice issued under the Beneficial Ownership Transparency Act (the "BOT Act").

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4.3 We express no opinion as to the meaning, validity or effect of any references to foreign (i.e. non-Cayman Islands) statutes, rules, regulations, codes, judicial authority or any other promulgations and any references to them in the Securities Purchase Agreement.

4.4 We reserve our opinion as to the extent to which the courts of the Cayman Islands would, in the event of any relevant illegality or invalidity, sever the relevant provisions of the Securities Purchase Agreement, and enforce the remainder of the Securities Purchase Agreement or the transaction of which such provisions form a part, notwithstanding any express provisions in the Securities Purchase Agreement in this regard.

4.5 Under the Companies Act, the register of members of a Cayman Islands company is by statute regarded as prima facie evidence of any matters which the Companies Act directs or authorises to be inserted therein. A third party interest in the shares in question would not appear. An entry in the register of members may yield to a court order for rectification (for example, in the event of fraud or manifest error).

4.6 In this opinion letter the phrase "non-assessable" means, with respect to shares in the Company, that a shareholder shall not, solely by virtue of its status as a shareholder and in absence of a contractual arrangement, or an obligation pursuant to the memorandum and articles of association, to the contrary, be liable for additional assessments or calls on the shares by the Company or its creditors (except in exceptional circumstances, such as involving fraud, the establishment of an agency relationship or an illegal or improper purpose or other circumstances in which a court may be prepared to pierce or lift the corporate veil).

Except as specifically stated herein, we make no comment with respect to any representations and warranties which may be made by or with respect to the Company in any of the documents or instruments cited in this opinion or otherwise with respect to the commercial terms of the transactions, which are the subject of this opinion.

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement and to the reference to our name under the headings "Taxation" and "Legal Matters" and elsewhere in the Registration Statement. In giving such consent, we do not thereby admit that we come within the category of persons whose consent is required under Section 7 of the U.S. Securities Act of 1933, as amended, or the Rules and Regulations of the Commission thereunder.

Yours faithfully

/s/ Maples and Calder (Hong Kong) LLP

Maples and Calder (Hong Kong) LLP

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Director's Certificate

To:	Maples and Calder (Hong Kong) LLP
	26th Floor, Central Plaza
	18 Harbour Road
	Wanchai, Hong Kong

19 November 2024

Canaan Inc. (the "Company")

I, the undersigned, being a director of the Company, am aware that you are being asked to provide a legal opinion (the "Opinion") in relation to certain aspects of Cayman Islands law. Capitalised terms used in this certificate have the meaning given to them in the Opinion. I hereby certify that:

1            The amended and restated memorandum and articles of association adopted by a special resolution on 4 October 2019 and effective immediately prior to the completion of the Company's initial public offering of American depositary shares (the "Memorandum and Articles") remain in full and effect and are unamended.

2            The Board Resolutions were duly passed in the manner prescribed in the Memorandum and Articles (including, without limitation, with respect to the disclosure of interests (if any) by directors of the Company) and have not been amended, varied or revoked in any respect.

3            The authorised share capital of the Company is US$50,000 divided into 1,000,000,000,000 shares of par value US$0.00000005 comprising of (i) 999,643,050,556 Class A Ordinary Shares of a par value of US$0.00000005 each, (ii) 356,624,444 Class B Ordinary Shares of a par value of US$0.00000005 each, and (iii) 125,000 series A preferred shares of a par value of US$0.00000005 each, and (iv) 200,000 Series A-1 Preferred Shares.

4            The shareholders of the Company have not restricted or limited the powers of the directors in any way and there is no contractual or other prohibition (other than as arising under Cayman Islands law) binding on the Company prohibiting it from issuing and allotting the Shares or otherwise performing its obligations under the Registration Statement and the Securities Purchase Agreement.

The directors of the Company at the date of the Board Resolutions and at the date hereof were and are:

Nangeng Zhang

Wenjun Zhang

Hongchao Du

Zhitang Shu

Yaping Zhang

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Prior to, at the time of, and immediately following the execution of the Securities Purchase Agreement the Company was, or will be, able to pay its debts as they fell, or fall, due and has entered, or will enter, into the Securities Purchase Agreement for proper value and not with an intention to defraud or wilfully defeat an obligation owed to any creditor or with a view to giving a creditor a preference.

Each director of the Company considers the transactions contemplated by the Registration Statement and the Securities Purchase Agreement to be of commercial benefit to the Company and has acted bona fide in the best interests of the Company, and for a proper purpose of the Company in relation to the transactions the subject of the Opinion.

No interest in the Company constituting shares, voting rights or ultimate effective control over management in the Company is currently subject to a restrictions notice issued under the BOT Act.

To the best of my knowledge and belief, having made due inquiry, the Company is not the subject of legal, arbitral, administrative or other proceedings in any jurisdiction and neither the directors nor Shareholders have taken any steps to have the Company struck off or placed in liquidation. Further, no steps have been taken to wind up the Company or to appoint restructuring officers or interim restructuring officers, and no receiver has been appointed in relation to any of the Company's property or assets.

I confirm that you may continue to rely on this Certificate as being true and correct on the day that you issue the Opinion unless I shall have previously notified you personally to the contrary.

[signature page follows]

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Signature:	/s/ Nangeng Zhang
Name:	Nangeng Zhang
Title:	Chairman and Chief Executive Officer

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