Abstract:Recently, with the rapid development of online social network services, such as Weibo, Twitter, and Facebook, social networks pervade nearly every aspect of our daily life. Social networks connect all aspects of our social and economic life. The role of social networks has been rapidly becoming ubiquitous platforms of communication and making connections. It plays an important role as indispensable tools for professional networking, social recommendations, or online advertisement. Internet-based social networks consist with the most important virtual society of maintaining social relationships. Meanwhile, social networks also have far-reaching effects for national security and social development. With billions of different connections, individuals constitute a“relational structure” on social networks, which includes a large number of complex relationships, such as social communities, social ties, or linkage farms, etc. Based on the relationship of social network structure, the connected individuals gather with a large number of ongoing events. They influence each other by interactions. Thus, the individuals form a variety of networking crowds with common behavioral characteristics. Based on relational structure and social networking crowds, various kinds of information has been quickly published and disseminated, which leads to the formation of the social media. Virtual world gives feedback to the reality societies. Therefore, the virtual and reality keep interacting and influencing to each other. To fully understand the various aspects of social networking operating mechanism, this paper focuses on the analysis of a series of key and tightly knitted elements in the evolution of social networks:（1） the structural properties of social networks and their evolution;（2） social groups and their interaction law; and（3） social networking information and its dissemination. In this paper, we first introduce the scientific connotation and related research progress of these three issues, and the prospects for future research.