Abstract: The Haihe River Basin experienced a basin-wide extreme flood, known as the "23·7" flood, due to the very heavy rainfall caused by northward movement of No. 2305 Typhoon Doksuri and its interaction with cold air. To effectively respond to this disaster providing critical flood decision supporting, a flood analysis model was developed for the operated flood storage and detention areas by the Research Center on Flood & Drought Disaster Prevention and Reduction(Flood and Drought Disaster Defense Center) of the Ministry of Water Resources, the China Institute of Water Resources and Hydropower Research(IWHR).This study utilized the FASFLOOD software based on a general high-performance flood analysis and calculation tool developed by IWHR, in conjunction with multi-temporal SAR image monitoring and analysis results, to simulate the flood routing in the Gongquxi Flood Storage and Detention Area within the Haihe River Basin. The results comprehensively depict the evolution process and retention distribution of floods in the Gongquxi Flood Storage and Detention Area, providing scientific reference for decision-making and management related to the opeartion of flood storage and detention areas, thereby effectively supporting flood defense efforts.