The purpose of this article is to explore the relationship between social media and knowledge sharing from the social capital perspective. The power distance introduced as moderating variable to explore its effect on the path of social media and knowledge sharing. Based on the structural, relational and cognitive dimensions included in social capital theory, this article select social networks, trust, and shared language as mediating variables, power distance as moderating variable, and applying partial least-square (PLS) regression and WarpPLS 5.0 software to analyze data. The analysis results shows that social media not only affects knowledge sharing directly, but also positively affects knowledge sharing through the mediating role of social networks, trust and shared language. Moreover, power distance is negatively moderate the relationship between social media and knowledge sharing.