Abstract: Flood storage and detention areas are critical components of the river basin flood control system with indispensable flood control function.In recent years, significant alterations in rainfall patterns, flood conditions, flood control projects, and social conditions have introduced new requirements for flood storage and detention area layout optimization.Therefore, a model for calculating excess flood volume was developed, and the layout optimization method and evaluation index system of flood storage and detention areas under changing environment were proposed.Focusing on the Chuhe River Basin, we quantitatively analyzed the evolution law of flood storage and drainage systems and the spatio-temporal distribution characteristics of excess flood volumes.And then we studied the current layout rationality and layout optimization of flood storage and detention areas in the Chuhe River Basin.The results indicated that the current layout was difficult to effectively manage 77 million cubic meters excess flood volumes from upstream regions between Jinji and Chizhen reach when rainstorm centers were located in the upstream area during the 2020 flood.Under the guidance of the proposed layout optimization method, the temporal and spatial distribution of excess flood volumes was further optimized through interventions such as river dredging and flood control water level adjustment.Ultimately, the layout optimization scheme of flood storage and detention area was selected based on comprehensive comparison from the aspects of flood diversion capacity and social and economic impact, which systematically solved the contradiction between excess flood volumes and available storage capacities in the Chuhe River Basin.The results can provide valuable reference for flood control planning revision or flood control projects design in the Chuhe River basin, and also provide methodological and technical reference for similar researches in other river basins.