Based on the hourly precipitation, process precipitation, digital elevation model, land use, soil type and other data of 28 national meteorological stations and regional automatic meteorological stations in Puhe River Basin, the flood inundation simulation and effect test of the historical rare rainstorm and flood process from 21:00 on June 19 to 20:00 on June 22, 2020 are carried out by using the flood area hydrodynamic model. The simulation results show that: 1) The overall fitting degree of the simulated water level and the measured water level in the whole process is high, and the certainty coefficient DC reaches 93.22%. 2) The inflow from the upper reaches of Puhe River was small, and the continuous heavy precipitation was the main reason for the high flood level. The simulation showed that the water level in the middle and upper reaches of Puhe River Basin increased significantly, and the maximum water level simulated by Shijiao hydrological station was 7.61 meters, which was consistent with the measured water level of 7.14 meters. 3) FloodArea hydrodynamic model can accurately reflect the performance of PuHe basin rainstorm flood process, to flood example can intuitively reflect the scope of flood, submerged depth of the space difference, and submerged depth and the deterministic coefficient of the measured water level is higher, one by one hour submerged depth of a spate of flood forecast warning has a certain instruction significance.