The internet technology has re-distributes the social expression rights，and the formation of the grass-root opinion leaders is caused conjointly by the personal information source，knowledge level，personal values，social responsibility and many other factors. The benefits，values，and demands of most of the netizens were realized by the influence of the grass-root opinion leaders. The current study analyzed the characteristics of the opinion leaders and their influence in different stage of public events. We also discussed the relation between the influence of opinion leaders and its elements. In the formation of the influence on microblog public opinion，number of the followers，number of comments were found to be positively related to microblog influence，and number of microblogs and portion of original microblog were the two indicators that positively correlated to microblog influence.