Abstract: Aiming at the problem of lack of systematic study on the whole process of extreme storm flood disasters,this paper puts forward a GIS-based urban storm flood simulation analysis method. Based on the division of sub-watersheds,the“7·20”torrential rain disaster in Zhengzhou City,Henan Province is simulated in the order of rainfall-runoff-inundation,and the disaster situation of buildings and traffic in the study area is evaluated. By comparing the calculation results of the model with satellite image data,it shows that it is basically consistent with the actual range and depth of the flood. It can be seen that the model proposed in this paper can quickly deduce and simulate the largescale flood inundation in Shifo Town,Zhengzhou City under the emergent situation of missing or low-accuracy data,so as to provide reference for the simulation of urban extreme storm flood disasters,and has practical application values.