Abstract: Web2.0 technology constitutes an important reality of contemporary Chinese value consensus problem. In this paper,we selected "5·28 Zhaoyuan McDonald's case" as a representative case,and analyzed the constructive methods and factors of value discourse in weibo field through Xinlang Weibo users' blogs. The study found that:the early group reflection of social value is restricted by both institutional and symbolic factors. The former pushed the related hot topics to the edge space of weibo field by some system designs such as topic-time limitation system,topic management system and keyword handling system. The later suppressed the enthusiasm of weibo users by the identity tag of "Keyboard man". Both together lead to the value consensus,which develops from bottom to top and from inside out,and lacks the support of stable spatial foundation and symbol capital.