Exhibit 99.4

October 13, 2017

Building G1, No.999 Dangui Road

Pudong New District, Shanghai 201203

People’s Republic of China

Dear Sirs:

Pursuant to Rule 438 under the Securities Act of 1933, as amended, I hereby consent to the references to my name in the Registration Statement on Form F-1 (the “Registration Statement”) of PPDAI Group Inc. (the “Company”) and any amendments thereto, which indicate that I have accepted the nomination to become a director of the Company. I further agree that immediately upon the Securities and Exchange Commission’s declaration of effectiveness of the Registration Statement, I will serve as a member of the board of directors of the Company.

Sincerely yours,

/s/ Jimmy Y. Lai

Name: Jimmy Y. Lai