“Weibo” is a type of social network service in China. This study focuses on people’s addictive use of Weibo in China and investigates the relationships among expected outcomes of Weibo use, deficient self-regulation, Weibo usage and Weibo addiction. Social cognitive theory was applied as the guiding theoretical framework in the current study. Participants from a public university in China were asked to fill out the measures. Exploratory factor analysis and multiple regression analysis were used to answer the research questions. The results suggest that participants have expected self-reactive outcome, expected status outcome, and expected novelty outcome in Weibo use. Expected self-reactive outcome positively predicted deficient self-regulation and all the dimensions of Weibo addiction. Weibo usage also positively predicted deficient self-regulation and all the dimensions of Weibo addiction. Research implications and future research directions were discussed in this study.