Social networking services （SNS）is a service which based on the theory of six degrees of separation to construct a friend group associated with its community and expand its network of people via “friends of friends”[1]. Up to present, however, there exists lots of problems like, low user authenticity, week reliability, lack of social stability and the function of recommending potential friends is still imperfect .Based on the above issues, in this paper we present a social networking system called mobile SNS which based on China Mobile “Fetion rebort” to construct a real, stable and reliable network. The core ideology of this paper is one algorithm which based on the social network and then use "Sim Rank algorithm" to calculate the degree of similarity in the community between the user and the tightness of individuals finally catch sight of the potential friends and recommend him or she to the user in need.