Social Network Site is the fascinating hotspot in China. Led by Facebook and other social networking sites in the West，the global social networking site in the past two years are growing rapidly. The SNS-based new social network sites continue to emerge in recent years in China.In 2009 social network site users and traffic surge attract many business giants.Some network traditional communities have launched SNS elements. This article outlines the background and the development of social network sites in China and describes the features of the Chinese social network sites viewing from the new media. Based on survey data this paper analysis the SNS users and their behavior，introduces the trend of SNS. It should be attach importance to social network site in the national security challenges，threats to personal information security，homogeneous competition severe and illegal dissemination of information etc.