Abstract: To fully support the decision-making and forecasting efforts of Dongdian storage-detention area operation during the "23·7" extreme flood in the Haihe River Basin, a 1D-2D coupled hydrodynamic model was constructed based on the highperformance flood analysis software IFMS/Urban developed independently by China Institute of Water Resources and Hydropower Research. This model utilized real-time monitoring and water regime forecasting data to continuously simulate and provide rolling predictions of flood evolution in Dongdian storage-detention area. It has been proven through practical applications that the flood evolution model constructed in this paper has high accuracy in simulation and prediction, with simulation results closely matching the flooded area detected by remote sensing and the real-time feedback from the front line. This model can thus reflect the actual flood evolution process in the storage-detention area, accurately predict future dynamic changes, and provide timely flood warnings for the key downstream areas, effectively supporting the flood prevention work.