Abstract: Based on the natural disaster risk assessment method, evaluation index factors are selected from three aspects: disaster causing factors, disaster prone environment, and disaster bearing body to construct a flash flood disaster risk index system. The Analytic Hierarchy Process is used to determine the weights of each index, and the index is normalized to form the results of flash flood disaster risk assessment. By collecting historical case data of flash flood disasters in Zhejiang Province, the risk assessment results of the province were divided into four risk levels according to the degree of risk. The research results were applied to meteorological risk warning of flash flood disasters. Based on meteorological numerical forecasting results, areas with flash flood disaster risks in the future can be predicted and warned in advance, effectively extending the prediction period of flash flood disasters.