Exhibit 15.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in the Registration Statement (Form S-8 No. 333-177273), pertaining to the 2010 Share Incentive Plan of 21Vianet Group, Inc. of our report dated April 18, 2012, with respect to the consolidated financial statements of 21Vianet Group, Inc., included in this Annual Report (Form 20-F) for the year ended December 31, 2011.

/s/ Ernst & Young Hua Ming

Shanghai, People’s Republic of China

April 18, 2012