In order to discover the key factors for the successful implementation of the collaborative management of disaster prevention and mitigation in coastal cities and their causal coupling, based on the hypothesis, the main factor analysis method was used to analyze the key factors of the various subsystems of disaster prevention and mitigation, and to verify the correlation between the main factors and the successful implementation of coordinated governance for disaster prevention and mitigation in coastal cities. Interpretative structural model (ISM) is used to explore the coupling relationship between subsystems and key factors within each subsystem. The results show that there have 6 factors, including emergency organization coordination, plan construction coordination, monitoring and early warning coordination, information sharing coordination, emergency command coordination, and emergency resource coordination are positively related to the successful implementation of coastal city disaster prevention and mitigation collaborative governance; emergency rescue coordination and emergency decision-making coordination are not directly related to the successful implementation of disaster prevention and mitigation collaborative governance in coastal cities. When the main factors work together, the impact on the successful implementation of disaster prevention and mitigation collaborative governance in coastal cities is not obvious. There are obvious hierarchical relationships and clear influence paths between key factors within each main factor.