Rumor is a complex social phenomenon, usually referring to ″a specific (or topical) proposition for belief without secure standards of evidence being present.″ With the development of media revolution both in depth and width, the current information communication in China has entered the so-called ″micro era,″ that is, an era of ″micro-miniature″ media communication which is marked by the rise of new media or we-media such as micro-blog, WeChat and mobile terminal. As a by-product of the ″micro era，″， internet rumor spreads so rapidly that it breaks through the linear communication of traditional media and netlike communication of network media, and then forms its distinctive chain-like, orbicular and arborescent communication structure, which makes possible the polymerization and fission of internet rumors. It turns out that the outbreak and the viral diffusion of internet rumors increasingly disturb the social order, leading to the enlargement of social risks and their malignant development. Therefore, in order to cope with those social risks and threats brought by the high-risk society, it is necessary to carry out the research on internet rumors and to improve the capability in managing them. It needs to be pointed out that in the micro era the network rumor must have certain features to spread far and wide. It must involve topics concerned by the public and meet the receivers' psychological expectations. The importance of the issues or the degree of public concern is a necessary condition for rumors to breed and spread. In the era of information explosion, once the mythical importance of an event, the universalized social risk and the information vacuum in risk status and public anxiety are mixed together with the revolutionary function of new media and we-media, internet rumors will inevitably breed and spread quickly. Of course, the wide-spread of internet rumors in the ″micro era″ is also closely related to the decline of the government's credibility and the marginalization of mainstream media. The transmission mechanism of Internet rumors refers to the systematic function of rumor spreading in the network society, in which they adapt to the constantly changing internet environment so as to spread in a regular and distinctive mode combined with self-coordination, integrated development, and expansion of influence. In this paper, a case study method is adopted to analyze the ″Zhongtai Incident″ in Yuhang, Hangzhou. The findings of the transmission mechanisms of Internet rumors are mainly shown as follows: First of all, the fact that the netizens' rights and benefits are aggrieved or deprived, combined with the indignation and anxiety caused by such deprivation, is the triggering mechanism of internet rumors, especially when the indignation of netizens opens the information cascades of rumor. Secondly, information cascades and conformity psychology are the reinforcement mechanism of Internet rumor transmission, among which the conformity behavior in the network society and ″the spiral of the silence effect″ inflames the spread of rumors. Thirdly, the group polarization based on conformity behavior is the social contagion and diffusion mechanism of Internet rumors. Fourthly, biased absorption and netizens' exaggeration are the distortion mechanism of Internet rumors. Finally, the dissipation mechanism of Internet rumors relies on the active and effective measures of the government, such as holding press conferences, releasing live videos, and penalizing the rumormongers. Therefore, quick government response, information transparency of emergency, efforts to relieve public panic and punishment of the rumormongers are all the necessary components for rumor dissipation.