Abstract: Water engineering groups play a crucial role in the river basin flood control system.Strengthening the optimal operation of reservoir groups for flood control can further tap into the flood control potential and improve the joint flood control and regulation capacity of water projects.Traditional joint optimal flood control scheduling models face excessive computation time due to complex connections between reservoirs,failing to meet real-time operation demands.An acceleration method combining structural dimension reduction and unit decision time interval optimization was proposed to reduce computational load and improve solving efficiency.Taking a hybrid-connected system with 4 reservoirs in the Pihe River Basin as the research object,a joint optimal flood control scheduling model was constructed,and a case study was conducted with the flood event from July 17 to 23,2020.Results show that,compared with actual operation,the proposed model better utilizes the water storage capacity of reservoirs,reducing the peak discharge at the downstream Hengpaitou Section from 4 590m³/s (measured) to 3 955m³/s.After adopting the acceleration method,the deviation of simulated peak discharge at Hengpaitou Section from that before acceleration is only 60m³/s (deviation rate<1.5%).Meanwhile,computational load is significantly reduced:the model solving time shortens from 1 200s to 182s,with an 85% efficiency improvement.The acceleration method effectively addresses the long-time consumption issue of traditional models while ensuring optimization accuracy,providing a feasible technical path for the engineering application of joint optimal flood control scheduling models for hybrid-connected reservoir groups.