21Vianet Group, Inc. Filed Its Annual Report on Form 20-F

21Vianet Group, Inc. (Nasdaq:VNET) ("21Vianet" or the "Company"), a leading carrier-neutral Internet data center services provider in China, today announced that it has filed its annual report containing its audited consolidated financial statements on Form 20-F for the fiscal year ended December 31, 2017 with the Securities and Exchange Commission on April 12, 2018. The annual report can be accessed on 21Vianet's investor relations website at http://ir.21vianet.com/. The Company will provide hard copies of the annual report, free of charge, to its shareholders and ADS holders upon request.

About 21Vianet21Vianet Group, Inc. is a leading carrier-neutral Internet data center services provider in China. 21Vianet provides hosting and related services, cloud services, and business VPN services, improving the reliability, security and speed of its customers' Internet infrastructure. Customers may locate their servers and networking equipment in 21Vianet's data centers and connect to China's Internet backbone through 21Vianet's extensive fiber optic network. 21Vianet operates in more than 30 cities throughout China, servicing a diversified and loyal base of nearly 5,000 hosting and related enterprise customers that span numerous industries ranging from Internet companies to government entities and blue-chip enterprises to small- to mid-sized enterprises.

Investor Relations Contacts:21Vianet Group, Inc. Julia Jiang+86 10 8456 [e-mail]

ICR, Inc. Jack Wang+1 (646) [e-mail]