This report takes “post-truth” as the entry point to examine the phenomenon of emotional public opinion in cyberspace triggered by such hot news as the “Lei Yang Case” in recent years and，in light of the characteristics of the expression，formation and dissemination of public opinions in cyberspace in the Internet era and the controversies over and problems in the work and the method of regulation of public opinion in cyberspace in China，puts forward suggestions on ways of preventing the wanton spread of irrational emotion over hot events in cyberspace.