Abstract: There is a rare super rainstorm in history occurred in Henan Province from July 17 to 23 in 2021, which suffered severe flooding, resulting in heavy casualties and property losses, especially in Zhengzhou City. In order to support the relevant work of the Zhengzhou "7·20" extreme rainstorm disaster investigation team of the State Council, a rainstorm and flood model in the central urban area of Zhengzhou City is developed by using IFMS/Urban flood analysis software, and the water accumulation in the central urban area is simulated, the water level of the main inland rivers in Zhengzhou City is analyzed. The research results provide a basis and reference for revealing the causes of disasters and reconstructing disaster scenarios.