Objective: In public health emergencies, how to quickly establish trust and convey authoritative and professional medical information through appropriate channels and methods in society is the focus of emergency response. Methods: By analyzing the public opinion index of new online media, this study explores the peak and trend characteristics of social communication conducted by medical experts in the outbreak of COVID-19, and analyzes the effectiveness and characteristics of information transmission. Results: The medical information voiced by authoritative experts has aroused high social concern, showing a rapid surge, sustained high trends, and peaks are closely related to the critical nodes of the epidemic. Conclusion: Effective medical information transmission under the outbreak needs to reflect authority and professionalism in all aspects of social communication, and the social communication strategy in emergency prevention and control of major epidemic situations can be further optimized with data support.