Abstract: To construct the social network of Micro-blog users has become one of the most important method to analyze micro-blog data. However, due to the uncertainty of the behavior of users in the process of information release and dissemination, it is hard to construct effectively the social network of Micro-blog users. Based on the uncertainty theory, the paper proposes a rough set based dynamic cognitive technology to handle the incomplete and massive information of micro-blog, complete the calculation and analysis of behavior of users, and construct the social network of Micro-blog users. On this basis, the development of network events in micro-blog is analyzed combined with the method with operation, theme and emotion analysis.