—At present, public opinion research on early warningmodel always use almost all history data, which can’t predict thedevelopment trend of events timely. The paper presents an earlywarning model of public opinion based on the logistic model todynamically describe the propagation rule and warn timely onpublic opinion. Regarding the hot words in micro-index as theresearch object, the paper studied the logistic model bymathematical modeling method, researched the characteristicpoint-in-time calculation of public opinion diffusion curve andmonitoring and early warning of public opinion. The method wasverified correctly and efficiently with the time series of thedevelopment trend of an incident in Sina micro-blog and the resultshowed that the study is practically useful.