Abstract: With the development of internet technology, social media has formed a complex internet society, with large-scale, complicated compositions and diversified forms. In the internet society, opinion leaders exert a crucial dissemination impact on the evolution of public opinion. Mixed with diversified rumors and false information, an emergency can easily trigger a public opinion crisis. The opinion leaders give play to their dissemination impact when internet marketers spread rumors and when official microblogs dominate the public opinion field. The internet marketer refers to people who spreading rumors online to earn big money, while official microblog refers to people or government organization who dispelling rumors to restore the truth. In this paper, the evolution process of public opinions is divided into two stages, each with different modeling methods to simulate the dissemination influence of opinion leaders in different stages. The first stage is when a public opinion crisis erupts, that is,when the public opinion crisis appears out of nothing. Regarding this stage, the paper mainly analyzes the diffusion influences of internet marketers. Based on the Susceptible-Infected-Recovered model (SIR), the paper aims to set up a model that considers the diffusion impact of internet marketers. In the new model, the three groups in the original SIR model are divided into four categories, thus broadening considerations regarding the dissemination impact of internet marketers. The second stageindicates the stage of quelling the public opinion crisis, namelywhen a public opinion crisis disappears completely. An analysis of the disproval impact of official microblogs at this stage is involved in this paper. Based on the Lotka-Volterra competition relationship model, how official microblogs give play to theirdisproval impact and compete with internet marketers isexamined. According to the measurement of the equilibrium point stability of the Lotka-Volterra model, there are four types of competition results between internet marketers and official microblogs, and the optimization result is that positive official microblogs win in the competition process. The paperconducts a simulation analysis of a staged model by combining specific public opinion cases. The research results show that the staged modeling of public opinion evolution can reflect the authentic evolution process. By emphatically analyzing the simulation of the communication influence of different opinion leaders, it is suggested that the government should improve its capacity to govern public opinion crises in four respects: ①the capacity to identify internet marketers,②the capacity of monitoring rumor propagation, ③the capacity of monitoring rumor propagation, ④the capacity of the competitiveness of official microblogs. When governing public opinion crises, the government should consider all aspects mentioned above in order to improve the governmental capacity to cope with emergencies.

Key words: opinion leader, dissemination impact, disproval impact, staged modeling