After the occurrence of an emergency， it is of great practical significance to accurately analyze the emotional state of netizens and guide the evolution of the emotional state of netizens to control public opinion on an emergency and maintain social stability. According to the characteristics of netizens’ comments on emergencies， a complete set of netizens’ emotional states are constructed， and different emotional sets are established from the perspectives of stakeholders and emergencies themselves. According to the transmission mode of epidemic model， the evolution models of netizens’ emotional states EP-SIS and EO-SIS are established based on susceptible-infectious-susceptible（SIS） epiddemic model. An empirical study is made on the model by using the Weibo comments of netizens on the “New pneumonia virus”， and the weight of influencing factors is obtained. The negative emotion conversion rate of the model for netizens is 0.72. EP-SIS and EO-SIS， the emotional evolution models of netizens in emergencies constructed in this study， can intervene from different angles to make the negative emotional state of netizens evolve in emergencies.