The owners of social networks and researchers who are interested in text information processing recognize and use genre to identify network resource and participating in mutually understood communicative acts. Many studies have shown that, the genre can improve the ability to access resource in the information pool, such as music and book community. Some linguists describe genre as a distinctive type of communicative action, characterized by a socially recognized communicative purpose and common aspects of form. However, in the current studies, how to use genre to mark information is always a difficult thing. A discourse genre is a subtle and complex concept. To some extent, it represents perplexing relationship between a large number of communicative events among social network. In this paper the genre is seen as a multidimensional phenomenon and is denoted using vector. We use vector distance to measure the relationship strength of social networks communicative events. It can be proved automatic discourse classification according to genre in social information sharing, transfer and knowledge communication provides a higher level quality of service(QoS). Finally, we select movie community to investigate the key role of genre in classifying discourse and seizing users interests. The results show that user various behaviors stickiness in network community and discourse genre relationship intensity have potential common features. The more similar discourse genre is, the more similar of social network users all kinds of behavior. Through these we can identify new genre and illustrate that genres are used for coordinating information addressing aspects of coordination mechanisms such as divisibility, concurrency, accessibility and timing that help people improve the coordination of information process.