Abstract: Internet public opinion is the emotional expression of social political position and political attitude produced and held by the public on specific social emergencies in cyberspace. The evolution of Internet public opinion is the reflection of the change trend of Interne public opinion over time. The research on the evolution process of Internet public opinion can analyze the development process and development law of public opinion caused by emergencies in the Interne environment, and provide necessary theoretical support for the public decision-making departments to implement effective monitoring and early warning decision-making for public opinion events. Based on the traditional SEIR warehouse model of Internet public opinion communication, this paper constructs an improved SEIR model considering user's subject interest. Through the establishment of Internet public opinion evolution model, the key factors influencing the evolution of public opinion events are simulated and verified. The results show that the evolution of Internet public opinion in emergencies is not only related to the number of users and the status of users, but also has significant relationship with the subject interest and focus of network public opinion users. In the process of public decision-making, the government should not only strengthen the public opinion guidance for key users of Internet public opinion, but also constantly detect the core theme of Internet public opinion, fully disclose the topic focus information of public opinion, evacuate the blind area of public opinion, and guide and control the trend of public opinion.

Key words: user's topic interest, evolution of Internet public opinion, modelling, simulation