It is of great significance to explore the numerical prediction of urban waterlogging disasters for flood control, disaster alleviation and disaster assessment. Based on the triangular unstructured grid, a high-precision two-dimensional shallow water hydrodynamic model was established using the Godunov finite volume method. The model uses Roe scheme to calculate the interface flux, which can capture the dynamic boundary motion of flood. The model puts the hydrostatic pressure into the source terms to reduce the numerical solution of pseudo-oscillations caused by the terrain slope. The model also improves the dynamic boundary and negative water depth treatment method, which can effectively improve the accuracy and static water harmony of the model simulation. After the calibration of three examples, the model was applied to the simulation of surface flood evolution in Huntai Alley area, which is between the Hun River and Taizi River. The results showed that the changes of water depth and flow field were reasonable, under the condition of combined dam break the inundated area of different water depths was uniformly the largest. The simulation results verified the flow evolution process of rainfall flood in the urban area. It is proved that the model can be used to simulate the rainstorm water accumulation and surface flood evolution caused by urban precipitation in complex terrains, and the model can quickly provide water accumulation and waterlogging information for urban flood control and disaster alleviation.