Abstract: Regional flood impact assessment based on a urban development zone as a whole differs significantly from the flood impact assessment for independent construction projects in terms of evaluation targets, contents, and methods. Taking the Hubei Xishui Economic Development Zone as an example, exploring the technical route and evaluation focus of regional flood impact assessment. Based on the terrain characteristics, identifies the flood and waterlogging caused by heavy rain in adjacent small tributaries as the main source of flood. Higher flood standards are proposed based on the development zone planning and future development. The risk of potential floods in the surrounding basins to the development zone is calculated through hydrodynamic models. The results indicate that there is a high probability that the Xishui Economic Development Zone will be flooded due to flooding within the flood control standards, and it is recommended to adopt measures such as filling up the riverfront area to reduce the threat of floods to the Xishui Economic Development Zone. Regional flood impact assessment can provide technical support for flood risk prevention in the planning and construction of development zones through overall risk assessment. It also replaces individual approval of construction projects with advance approval of the entire development zone, improving administrative approval efficiency.