Abstract:With the explosive growth in the variety and size, social network has evolved into one of the well-liked channel for Internet users to search information, share interests, and interact with others in their individual networks. While popular with Internet users, social network has become ideal“laboratories” for social scientists to study human behavior. Understanding the behavior patterns of social network, users can provide insights for government and business to control and utilize the hidden power in social network. The research related to social network user behavior consists of two streams. The first group considers the social network as a specific information technology. Researchers employ the theories in the information technology field, such as the Technology Acceptance Model and Theory of Reasoned Action, to study the influential mechanism of various factors on user’ s acceptance and continued usage for social network. The second group considers the social network as a platform which provides a wide selection of services and applications. Researchers employ methods of mathematics, statistics, and econometrics to analyze the behavior patterns of the social network usage. This paper reviews the researches on user behavior in social network and provides directions for further study. By considering the social network as a specific information technology, Section 2 reviews the researches on the acceptance and continued usage behavior of social network technology. For the acceptance of social network technology, the Uses and Gratifications Theory, Technology Acceptance Model, Five-Factor Model of Personality, Social Impact Theory, Network Externality Theory, and Theory of Planned Behavior are introduced. For the continued usage behavior of the social network technology, the Expectation Confirmation Model, Perceived Value Theory, Flow Theory, and Uses and Gratifications Theory are introduced. We also briefly review the researches on the continued usage behavior of social network technology conducted with other social theories. By considering the social network as a service and application platform, we classify user behavior as individual behavior and social interaction behavior, and review the corresponding literatures respectively. For the individual behavior in the social network environment, Section 3 first introduces the research methods and contents of the existing literatures on the usage patterns. The results of these researches are also briefly summarized. Content generation behavior and content consumption behavior are two classical behaviors of individuals in the social network environment. We review the literatures about the social motivation, topic preference, and the language behavior when individuals generate contents in social network platform. We also review the literatures about browsing behavior, search behavior, and the question-and-answer behavior when users consume contents in social network. For the social interaction behavior, Section 4 reviews the literatures about the interaction relationship, interaction content, and interaction time patterns in the social network environment. The researches on the classification of user relationship and the definition of relationship strength are first introduced. We then introduce the influence of network characteristics such as homogeneity and reciprocity on the interaction content. We finally review the researches on the difference of the time patterns between offline environment and social network environment. The theoretical explanations of the differences are introduced. Section 5 presents conclusions and provides the directions of future research. For future research, one possible direction is to study user behaviors on the professional fields like scholarmate.com rather than the general social network websites like Facebook.com. Social network has been an important tool to innovative business strategy, and user modeling by considering the commercial features is an important direction for research. Because social networking has gone mobile, the further study should pay more attentions to user’ s mobile social networking behavior. Most of the existing literatures on user influence are based on network structure. Social influence identification with consideration of social characteristics is another broad research question.