As rapid development of social media, its dark sides have appeared. The social media addiction is an example. Based Uses and Gratifications Theory, this article explores the symptoms of weibo addiction and its formation mechanism by netnography. The results showed that: (1) some weibo users have the symptoms of addictive behaviors, such as withdrawal, loss of control, and life problems; (2) narcissism has an important role in the process of weibo addiction, which would have a stronger effect on content generator than content consumer; (3) some weibo users get addicted for relaxing anxiety, however, they get more anxious because of addiction; (4) The reviews have two sides. On one hand, the reviews are one kind of feedback of weibo posting, which satisfied the social needs, on the other hand, a Storytelling System is made up of the post and its reviews, which some weibo users become more dependence.