Abstract: This paper briefly summarizes the application of flood risk map and its compilation technology and methods. Taking Pingshan District of Shenzhen City as an example, based on the high-precision topographic data of 0.5 m grid, the hydrological model and two-dimensional hydraulic model are established. The accuracy of digital elevation model (DEM) of topographic map, terrain processing method, modelling method, design rainfall, calculation grid, simulation scale, etc. are deeply discussed. In addition, the surface confluence process under different rainfall conditions in the region is simulated in detail, and the flood risk distribution information is extracted, including the flooding depth, range, flow rate, flood occurrence, and water recession time process. Based on the simulation results, the urban high-precision flood risk map of the basin under different design rainfall conditions (from 2 years to 100 years recurrence) was drawn. High-precision DEM and two-dimensional hydraulic model are key elements to improve the accuracy and quality of urban flood risk mapping.