When the COVID-19 epidemic broke out, China carried out national defense mobilization, which was an emergency function of national defense mobilization. Because when the COVID-19 epidemic broke out, in order to reduce the harm of the epidemic, reduce the loss of people's lives and maintain social stability, China carried out emergency national defense mobilization, and quickly activated, requisitioned and deployed potential materials scattered in society to meet the needs of major crises. Therefore, when the COVID-19 epidemic broke out, China carried out national defense mobilization, which belongs to the emergency function of national defense mobilization.