Abstract: A microblog's semantic expansion and classification method was proposed by analyzing and researching microblog users,microblog text and microblog comments based on forwarding comments.Firstly,on the basis of analysis of the type of microblog users,microblogs were classified into six categories.Centered on information-publishing microblogs,a selection algorithm of microblog comments for screening microblog's effective comments was proposed.Then by virtue of microblog's semantic expansion and classification method based on forwarding comments,microblog's effective forwarding information was added into the microblog's semantics to improve the data sparseness.Finally,it enhanced the microblog classification performance.