Human flesh search as the means of social association of information by internet users，is an important manifestation of information autonomy and implementation of the right of expression. Although it plays an important role in the integration of information，it appears strong uncertainty of positive and negative effects of social based on the social considerations of the information order，the public opinion field and power relation. Purification of public opinion lay particular emphasis on the realization of the value of public opinion，and the value of public opinion is an important standard of the purification of public opinion. The purification mechanism of public opinion should consider the advantages and disadvantages of the old public opinion order and the new network information mechanism，strengthening the actual interaction effect between public opinion and the reality.