Abstract: This study addressed current deficiencies in spatially refined simulation of economic units across administrative regions in a river basin for assessment of the urban flood hazard. Focusing on the spatial distribution of refined economic indicators, and incorporating multiple data sources, an urban flood risk assessment system was constructed for the quantification of the level of flood risk vulnerabilityin the Shenzhen River basin (China). Analysis based on the proposed system revealed the following. ① A single datum was found insufficient for accurate simulation of the GDP density of the basin, and combining multisource data representsa more efficient approach for performing spatial refinement of GDP. ② A high degree of consistency was evident in termsof the spatialization of GDP density and secondary and tertiary industries in the Shenzhen River basin, with the highest density of production values reaching 6 172.14 million yuan/km². ③ The level of vulnerability was found to vary oneither side of the Shenzhen River basin. The vulnerability to flooding/waterlogging on the Shenzhen side of the river is substantially higher than that on the Hong Kong side, and the area of high vulnerability comprises approximately 8.8% of the total basin area. The results of this study could help both identify the hazard intensity and degree of damage and improve accuracy in urban flooding/waterlogging risk assessment.