The study analyzed the mechanisms of rumor generation，transmission，and intervention based on the data of rumors appeared in the hottest public events from 2010 to 2012. It was found that online rumors have limited impact on the public opinion duration，but they have great effect on the public attention. The study also reveals that certain types of public events are more likely to facilitate rumor spreading，and warning and judgments should given in advance. In the complex communication environment，the appeared-authenticity of online information gives the credibility of administration greater challenges，so the government should encourage social power to participate in refuting rumors in order to enhance the effect of communication.