Social organizations can play complementary and supplementary roles in the governance of public health emergencies. In the prevention and control of COVID19, the roles of social organizations are obviously inadequate and unbalanced, but the current institutional theory and governance theory cannot explain such phenomena rationally. Based on the grounded theory, this paper analyzes the mobilization policy texts, and reveals that government mobilization is a kind of “adaptive mobilization” with the characteristics of “adapting” to the needs of epidemic prevention and control, the development level of social organizations, and the daily work of the government. Further case analysis indicates that social organizations participate in the prevention and control of COVID19 at different levels, but their participation is hardly affected by the mobilization policy, which is a kind of “low response”. To boost the government’s mobilization of social organizations, it is crucial to not only strengthen the adaptability of mobilization policies to the actual needs of social organizations, but also intensify policy publicity and implementation monitoring.