Abstract: 【Objective】Explore new approaches to the safety pattern of urban rain and flood under the background of Sponge City then determine the inundated area and the amount of runoff. 【Method】Combine the quantitative analysis of SCS-CN hydrological model with the GIS space simulation tool, and set up the research and expression method of “data to space”. 【Result】Firstly get the distribution data of rainfall runoff of different kinds of land in the city of JiangDu by using the SCS-CN hydrological model. The second is the combination of the GIS space simulation and the SCS-CN model, and the distribution of the direct runoff of rainwater in the urban space. The third is use the GIS space simulation tool to simulate the three types of land use of rainwater which amount up, based on the various types of land use is calculated according to the runoff amount, intuitively reflect the waterlogged land of the built area. 【Conclusion】 The research indicates that the SCS-CN model combining with GIS tools can more effectively reflect the status of the city after the heavy rain water logging, easy to take targeted measures to build Sponge City.