Abstract: We analyse the collective behavior caused by rumors as well as the rumors per se using the grounded theory and build the impact factor model that how rumors can trigger collective behavior.After analysis we find that subjects involved in the collective behavior include those believing the rumors, those douting them and those that even don't know them after the spreading of the rumors.Whether people believing the rumors would be involved in the collective behavior or not is affected by the features of the rumors, the social public factors, the situation of the government as a source of information and the circumstance. Predicting the impact of others, behavior on themselves、conformity are the factors leading those douting or unkowing the rumors to the collective behavior, which are influenced by the rumors indirectly.