Microblog is a new Internet featured product, which has seen a rapid development in recent years. Researchers from different countries are making various technical analyses on microblogging applications. In this study, through using the natural language processing (NLP) and data mining, we analyzed the information content transmitted via a microblog, users’ social networks and their interactions, and carried out an empirical analysis on the dissemination process of one particular piece of information via Sina Weibo. Based on the result of these analyses, we attempt to develop a better understanding about the rule and mechanism of the informal information flow in microblogging.