In the outbreak of COVID-19 at the end of 2019, mainstream media, as an importantcommunication node and watchtower in the society, faced with a mixed public opinion field withthe participation of multiple communication subjects, highlighted their diversified responsibilitiesand roles, and played an important role as a social stabilizer. However, there are still shortcomings inpublicity methods, public opinion guidance, and public opinion handling. By sorting out the publicopinion guidance made by mainstream media in epidemic prevention and control, based on differentdifficulties faced by epidemic prevention and control, this paper explains the stage course, propagandacontent, strategies and methods, communication characteristics and discourse power behind publichealth emergencies of China's mainstream media.