Under the context of a risk society，it is necessary to mobilize social forces extensively，which will help to improve the efficiency of public health emergencies in emergency management to enhance social resilience in coping with various risks and crises. This research conducted one-on-one in-depth interviews with 27 volunteers in three dimensions:“the induction/hindrance of volunteer service”“the motivation of volunteer service”and“the sustainability of volunteer service”，and then conducted open coding，axial coding and selective coding on text data. After conceptualizing and categorizing the content analysis，we formed three levels of individual volunteers，volunteer service process and external influencing factors and constructed a model of influencing factors on public participation in volunteer service behavior in public health emergencies. Research has found that the core factors affecting public participation in volunteer services for public health emergency are: motivation for participation，organizational characteristics，interpersonal interaction，incentive mechanism， guarantee mechanisms，constraints，and service management. The findings have specific practical significance for improving the attractiveness and sustainability of volunteer services to the public，enhancing the quality of volunteer service work，and social emergency management capabilities.