Social media is considered to play an important role in promoting government responsiveness. However, it is impossible for the government to respond to all issues in the actual situation. Especially when encountering controversial social incidents, the local government usually evades responsibility due to damage to reputation or interests. This paper argues that when a controversial social incident occurs in China, the National News Media and Journalists (NNMJs)will work together with social media to encourage the local government to respond. The knowledge broker theory is used to analyze the functions of NNMJs. Three cases are selected from Sina Weibo, China's largest social media platform for multiple case studies. And 21 participants were interviewed. The results showed that NNMJs and social media played the role of knowledge brokers in social incidents. NNMJs played the functions of awareness, accessibility, engagement, and linkage in developing social incidents. And social media took the motivation part in most situations. Meanwhile, they functioned with the central government, social media, and local government forming a top-down management mechanism and bottom-up supervision mechanism system. And then promoted the local government to respond to the government actively.