In order to accurately simulate urban rainstorm flood process, an urban rainstorm flood dynamic model coupled with surface runoff and sewer flow was established. The model mainly includes two-dimensional surface runoff module, one-dimensional sewer flow module, surface runoff and sewer flow interaction module and key infrastructure inundation module. The two-dimensional surface runoff module used the two-dimensional shallow water equation and Horton infiltration formula to simulate the surface runoff process. The sewer flow module used TPA method and Godunov finite volume method to solve one-dimensional pipe flow equations and simulate complex flow patterns in urban drainage networks. The two modules were coupled using formulas based on the discharge and overflow capacity of street inlets. The model was applied to Gangxi drainage area in Qingshan District, Wuhan City. The accuracy of the model was verified by using the 5a return period rainfall waterlogging risk map of Gangxi drainage area, and the urban rainstorm flood process under the 100a return period rainfall was simulated. The results show that the model has good calculation accuracy, and the simulated water depth of over 88.8% of waterlogging points is consistent with the official published results. Under the condition of the 100a return period rainfall, the areas of moderate and severe waterlogging in the Gangxi drainage area account for 12.52% and 1.16% of the study area, respectively.