Community emergency social mobilization is an important means and support for emergency management of public safety. In the face of COVID19 epidemic, switching from social governance to public safety emergency management, strengthening and improving the community emergency social mobilization system and mechanism construction are the internal requirements of public safety emergency management and major epidemic prevention and control. Based on the current COVID19 major outbreaks scene, this article interprets the reality logic of emergency social mobilization, explores its main content and working mechanism, analyzes the special problems of grassroots social mobilization during the major outbreaks of COVID19, and puts forward optimization strategies combined with the actual case to provide strong support and reference for the further research of emergency social mobilization at the grassroots level.