In this study, the risk structure framework of online public opinion group polarization of public health emergencies in the ternary space is combined, as well as the causes and constraints of group polarization distributed in the same space. The number of online users with extreme opinions can indicate the risk of group polarization in accordance with the idea of phase change space. Moreover, a simulation model of group polarization of online public opinion of public health emergencies is developed. The system dynamics simulation of the model is carried out by using the software Anylogic and predicts the evolution trend of the model from the perspective of simulation. The research results indicate that the model built in this study can effectively simulate the formation and dissemination of extreme opinions in the online public opinion of public health emergencies, and the vital factors or constraints on the group polarization include emotional guidance, heat reduction, as well as and life pressure.