Using the MIKE model and the ArcGIS platform, spatial information grids for the natural and social attributes of flood risks were respectively constructed and superimposed. The subjective and objective weights were calculated using the analytic hierarchy process and the entropy weight method, and the comprehensive flood risk index was computed to conduct a risk assessment for three adjacent streets in Qinhuai District of Nanjing City. The results show that, under different rainfall intensities, the spatial distribution of the comprehensive flood risk index is mainly characterized by higher values in the northwest and lower values in the southeast, with relatively higher values in vulnerable and sensitive areas. As the rainfall intensity increases, the area with higher values of the comprehensive flood risk index continuously expands. The main waterlogging treatment points in the study area are all located in regions with higher comprehensive flood risk indices. The flood risk assessment based on spatial information grids can provide references for more refined and dynamic flood disaster risk assessment and flood management.