Following the rapid development of internet, ”blogs” have recently become one of the most popular media. However, the antecedents of blog users' behavior weren't identified. The research adopts social identity theory and flow theory, and investigates 287 blog users to verify the influence of interactivity, enjoyment, flow state, similarity, distinctiveness, blog identification on participative behavior and blog loyalty. The results indicate that interactivity and enjoyment will significantly positive affect participative behavior through flow state. Besides, interactivity and enjoyment will significantly positive affect blog identification. Therefore, similarity, distinctiveness will affect blog loyalty through blog identification. This study attempts to build the influence of attitudes on blog users' behavior model to provide some practical suggestions.