Abstract: Evaluating the influence of mainstream media micro-blogs can reveal high-impact media, control the source of public opinion, and provide reference for government managing public opinion. This paper takes 20 mainstream media micro-blogs as research samples, and 4 first-class indicators and 10 second-class indicators are selected to establish the evaluation index system of mainstream media micro-blogs influence under the background of public health emergencies. Then, factor analysis and cluster analysis are applied to evaluate and compare the influence of mainstream media micro-blogs. Under the background of public health emergencies, most of the information of the influence of micro-blogs can be reflected by three common factors, that is, the degree of attention, the degree of user activity and the characteristic factor of blogs. The influence level of microblog of 20 mainstream media can be divided into five types, namely, strength leading type, black horse type, comprehensive medium type, comprehensive backward type and inactive type. In addition, the People's Daily, which ranks first in influence scores, is selected for specific analysis in order to give some enlightenment to other media.

Key words: Mainstream media, Micro-blogs, Micro-blog influence, Evaluation index, Factor analysis, Cluster analysis