Micro-blog as an important part of the network media has become an important access to information for Netizens. Some hot topics have an immeasurable impact on the public opinion formation and dissemination, and also potential security risks are absolutely not underestimated. Collecting the relevant data in the micro-blog can provide data base for public opinion analysis. The study, social topic detection system based on micro-blog is mainly centered on the key technologies in the information capture and the Chinese handling of micro-blog. This study invokes the API of Sina micro-blog through three kinds of capture strategy, and then uses RMM reverse maximum matching algorithm to capture the information of micro-blog, after this using classification of self-build public opinion to do information classification of micro-blog for structured storage. At last this study finishes the research and implement of the system based on micro-blog. The system has realized the hot topics of timely capture, collection, classification, storage and retrieval which lay the foundation for further public opinion analysis.