Based on the statistics and analysis of the strategies and characteristics of science popularization performed by the three main-stream media in combating COVID-19, this paper summarizes several features of science popularization practice of these media in the epidemic in terms of adequate agenda setting, efficient presentation, diverse information sources and effect of media convergence. The advantages and characteristics of science communication are analyzed respectively for the three main-stream media, and the limitation is pointed out as “putting emphasis on knowledge but ignoring thoughts”. Finally the key roles and functions of main-stream media in emergency science popularization in the epidemic are summed up as the following: to release alerting signals of epidemic situation and reliable professional information through topic setting; to act as communicating bridge between science community and public through interviews and reprints, as well as the supply and demand intermediary of scientific information; to take advantage of their own prestige to become the appraiser of the professionality of science popularization information, the key dissemination node of qualified science popularization contents, and the concentration area of excellent popular science writers, so as to expand the influence of excellent science popularization products and to attach much importance on the leading role of scientific spirit.