SCHEDULE 13G

Amendment No. 0
21VIANET GROUP INC
Common Stock
Cusip #90138A921


Cusip #90138A921
Item 1:	Reporting Person - FMR LLC
Item 4:	Delaware
Item 5:	11,120,850
Item 6:	0
Item 7:	18,847,476
Item 8:	0
Item 9:	18,847,476
Item 11:	10.413%
Item 12:	    HC


Cusip #90138A921
Item 1:	Reporting Person - Edward C. Johnson 3d
Item 4:	United States of America
Item 5:	0
Item 6:	0
Item 7:	18,847,476
Item 8:	0
Item 9:	18,847,476
Item 11:	10.413%
Item 12:	IN




	SCHEDULE 13G - TO BE INCLUDED IN
STATEMENTS
	FILED PURSUANT TO RULE 13d-1(b) or 13d-2(b)



Item 1(a).	Name of Issuer:

		21VIANET GROUP INC

Item 1(b).	Name of Issuer's Principal Executive Offices:

		M5, 1 Jiuxianqiao East Rd
		Chaoyang District
		Beijing F4 100016
		China

Item 2(a).	Name of Person Filing:

		FMR LLC

Item 2(b).	Address or Principal Business Office or, if None,
Residence:

		82 Devonshire Street, Boston,
Massachusetts  02109

Item 2(c).	Citizenship:

		Not applicable

Item 2(d).	Title of Class of Securities:

		Common Stock

Item 2(e).	CUSIP Number:

		90138A921

Item 3.	This statement is filed pursuant to Rule 13d-1(b) or 13d-2(b)
and the person filing, FMR LLC, is a parent holding company
in accordance with Section 240.13d-1(b)(ii)(G).  (Note:  See
Item 7).

Item 4.	Ownership

	(a)	Amount Beneficially Owned:	18,847,476

	(b)	Percent of Class:	10.413%

	(c)	Number of shares as to which such
person has:

	(i)	sole power to vote or to direct
the vote:	11,120,850

	(ii)	shared power to vote or to
direct the vote:	0

	(iii)	sole power to dispose or to
direct the disposition of:	18,847,476

	(iv)	shared power to dispose or to
direct the disposition of:	0



Item 5.	Ownership of Five Percent or Less of a Class.

	Not applicable.

Item 6.	Ownership of More than Five Percent on Behalf of Another
Person.

	Various persons have the right to receive or the power to
direct the receipt of dividends from, or the proceeds from the
sale of, the Common Stock of 21VIANET GROUP INC.  No
one person's interest in the Common Stock of 21VIANET
GROUP INC is more than five percent of the total outstanding
Common Stock.

Item 7.	Identification and Classification of the Subsidiary Which
Acquired the Security Being Reported on By the Parent
Holding Company.

	See attached Exhibit A.

Item 8.	Identification and Classification of Members of
the Group.

	Not applicable.  See attached Exhibit A.

Item 9.	Notice of Dissolution of Group.

	Not applicable.

Item 10.	Certifications.

	By signing below I certify that, to the best of my knowledge
and belief, the securities referred to above were acquired in the
ordinary course of business and were not acquired for the
purpose of and do not have the effect of changing or
influencing the control of the issuer of such securities and
were not acquired in connection with or as a participant in any
transaction having such purpose or effect.  I also certify that,
to the best of my knowledge and belief, FIL Limited and its
various non-U.S. investment management subsidiaries
included on this Schedule 13G are subject to a regulatory
scheme substantially comparable to the regulatory scheme
applicable to the functionally equivalent U.S. institutions.  I
also undertake to furnish to the Commission staff, upon
request, information that would otherwise be disclosed in a
Schedule 13D with respect to FIL Limited and its various non-
U.S. investment management subsidiaries included on this
Schedule 13G.

Signature

	After reasonable inquiry and to the best of my knowledge and
belief, I certify that the information set forth in this statement
is true, complete and correct.

October 09, 2012
Date

 /s/ Scott C. Goebel
Signature

Scott C. Goebel
Duly authorized under Power of Attorney
effective as of June 1, 2008 by and on behalf of FMR LLC
and its direct and indirect  subsidiaries


	SCHEDULE 13G - TO BE INCLUDED IN
STATEMENTS
	FILED PURSUANT TO RULE 13d-1(b) or 13d-2(b)



	Pursuant to the instructions in Item 7 of Schedule 13G,
Fidelity Management & Research Company ("Fidelity"), 82
Devonshire Street, Boston, Massachusetts 02109, a wholly-
owned subsidiary of FMR LLC and an investment adviser
registered under Section 203 of the Investment Advisers Act
of 1940, is the beneficial owner of 7,726,626 shares or 4.269%
of the Common Stock outstanding of 21VIANET GROUP
INC  ("the Company") as a result of acting as investment
adviser to various investment companies registered under
Section 8 of the Investment Company Act of 1940.

	Edward C. Johnson 3d and FMR LLC, through its
control of Fidelity, and the funds each has sole power to
dispose of the 7,726,626 shares owned by the Funds.

	Members of the family of Edward C. Johnson 3d,
Chairman of FMR LLC, are the predominant owners, directly
or through trusts, of Series B voting common shares of FMR
LLC, representing 49% of the voting power of FMR LLC.
The Johnson family group and all other Series B shareholders
have entered into a shareholders' voting agreement under
which all Series B voting common shares will be voted in
accordance with the majority vote of Series B voting common
shares.  Accordingly, through their ownership of voting
common shares and the execution of the shareholders' voting
agreement, members of the Johnson family may be deemed,
under the Investment Company Act of 1940, to form a
controlling group with respect to FMR LLC.

	Neither FMR LLC nor Edward C. Johnson 3d,
Chairman of FMR LLC, has the sole power to vote or direct
the voting of the shares owned directly by the Fidelity Funds,
which power resides with the Funds' Boards of Trustees.
Fidelity carries out the voting of the shares under written
guidelines established by the Funds' Boards of Trustees.

	Pyramis Global Advisors, LLC ("PGALLC"), 900
Salem Street, Smithfield, Rhode Island, 02917, an indirect
wholly-owned subsidiary of FMR LLC and an investment
adviser registered under Section 203 of the Investment
Advisers Act of 1940, is the beneficial owner of 413,400
shares or 0.228% of the outstanding Common Stock of
21VIANET GROUP INC as a result of its serving as
investment adviser to institutional accounts, non-U.S. mutual
funds, or investment companies registered under Section 8 of
the Investment Company Act of 1940 owning such shares.

	Edward C. Johnson 3d and FMR LLC, through its
control of PGALLC, each has sole dispositive power over
413,400 shares and sole power to vote or to direct the voting
of 413,400 shares of Common Stock owned by the
institutional accounts or funds advised by PGALLC as
reported above.

	FIL Limited ("FIL"), Pembroke Hall, 42 Crow Lane,
Hamilton, Bermuda, and various foreign-based subsidiaries
provide investment advisory and management services to a
number of non-U.S. investment companies and certain
institutional investors.  FIL, which is a qualified institution
under section 240.13d-1(b)(1)(ii), is the beneficial owner of
10,707,450 shares or 5.916% of the Common Stock
outstanding of the Company.

	Some or all of the shares of Common Stock of
21VIANET GROUP INC owned by the investment companies
at September 30, 2012 may include shares represented by
American Depository Shares.

	Partnerships controlled predominantly by members of
the family of Edward C. Johnson 3d, Chairman of FMR LLC
and FIL, or trusts for their benefit, own shares of FIL voting
stock. While the percentage of total voting power represented
by these shares may fluctuate as a result of changes in the total
number of shares of FIL voting stock outstanding from time to
time, it normally represents more than 25% and less than 50%
of the total votes which may be cast by all holders of FIL
voting stock. FMR LLC and FIL are separate and independent
corporate entities, and their Boards of Directors are generally
composed of different individuals.

	FMR LLC and FIL are of the view that they are not
acting as a "group" for purposes of Section 13(d) under the
Securities Exchange Act of 1934 (the "1934" Act) and that
they are not otherwise required to attribute to each other the
"beneficial ownership" of securities "beneficially owned" by
the other corporation within the meaning of Rule 13d-3
promulgated under the 1934 Act.  Therefore, they are of the
view that the shares held by the other corporation need not be
aggregated for purposes of Section 13(d). However, FMR
LLC is making this filing on a voluntary basis as if all of the
shares are beneficially owned by FMR LLC and FIL on a joint
basis.

	FIL has sole dispositive power over 11,899,650 shares
owned by the International Funds. FIL has sole power to vote
or direct the voting of 10,707,450 shares and no power to vote
or direct the voting of 0 shares of Common Stock held by the
International Funds as reported above.


	SCHEDULE 13G - TO BE INCLUDED IN
STATEMENTS
	FILED PURSUANT TO RULE 13d-1(b) or 13d-2(b)
	RULE 13d-1(f)(1)  AGREEMENT

	The undersigned persons, on October 09, 2012, agree
and consent to the joint filing on their behalf of this Schedule
13G in connection with their beneficial ownership of the
Common Stock of 21VIANET GROUP INC at September 30,
2012.

	FMR LLC

	By /s/ Scott C. Goebel
	Scott C. Goebel
	Duly authorized under Power of Attorney effective as
of June 1, 2008, by and on behalf of FMR LLC and its direct
and indirect subsidiaries

	Edward C. Johnson 3d

	By /s/ Scott C. Goebel
	Scott C. Goebel
	Duly authorized under Power of Attorney effective as
of June 1, 2008, by and on behalf of Edward C. Johnson 3d

	Fidelity Management & Research Company

	By /s/ Scott C. Goebel
	Scott C. Goebel
	Senior V.P. and General Counsel

	FIL Limited

	By /s/ Scott C. Goebel
	Scott C. Goebel
	Duly authorized under Power of Attorney
	effective as of June 1, 2008, by and on behalf
	of FIL Limited and its direct and indirect
	subsidiaries