Abstract：Online social anxiety refers to the negative interpersonal experience such as tension and fear that people perceive in social media platforms, Online social anxiety includes three dimensions: privacy concern, interaction anxiety and fear of negative evaluation. Online social anxiety can be studied by qualitative analysis, experimental induction and scales. Online social anxiety is determined by the characteristics of social media itself, individual characteristic factors, cyberbullying as well as culture. Meanwhile, online social anxiety would also lead to social media burnout, affect the frequency, direction and way of users’ self-disclosure online, and make those commit to online safety behaviors. Future researches of online social anxiety should develop or revise effective localized scales, explore its psychological mechanisms, pay attention to the possible causes of online social anxiety paradox, and promote the intervention of online social anxiety.