“Postmodern society”theory deconstructs the rational foundation of modern theory and presents the general characteristics of decentralization，de - authorization，and de - organization，which advocates the principles of difference and tolerance，negotiation and participation. During the social transition period，people encountered more complicated conflicts and apparent mindset changes from the characteristics of randomness， fluidity，risk，knowledge，variability，individuality and information presented by the“post - modern society”， this paper examines people’s confidence，calm，and rationality as well as changes in social mentality such as uneasiness and confusion under public health emergencies. To form a positive social mentality，it is necessary to strengthen the awareness of coping with social risks，guiding social mentality，recognizing collective memory，and optimizing system design to cultivate the excellent traditional Chinese culture，and to guide the development of positive social mentality with the core values of socialism. At the same time，it is necessary to reform the governance mechanism of public health emergencies to enhance the ability to handle these situations. We also recommend constructing a positive social psychological counseling system and increasing the positive collective memory of public health emergencies.