The invention relates to a specific group discovery and expansion method based on microblog data, and belongs to the field of social network analysis and data mining. The specific group discovery and expansion method comprises the following specific steps: collecting relevant group information; carrying out information integration and mapping; aiming at text data to carry out characteristic extraction; calculating a user similarity degree; carrying out the self-detection of a category group; and extracting the attributes of the specific group, judging a category, and carrying out group expansion. The specific group discovery and expansion method artfully avoids the problem that group identification can not be carried out since data is sparse or incomplete when a network model is used, inputs large-scale data calculation and is high in stability.