To accurately assess the impact of an individual reservoir on the downstream remote reservoir and flood control point, a joint flood control optimal scheduling model for the multi-reservoir system was developed. This model was constructed based on the basin-wide flood control requirements and the characteristics of each reservoir, to minimize the maximum outflow from the individual reservoir and the peak flood discharge at the flood control point. A hybrid algorithm, progressive optimality algorithm and successive approximation, was employed to optimize the model. Based on the optimal scheduling process, three indicators such as peak reduction contribution, flood retention contribution, and coordinated flood retention rate were proposed to evaluate the flood control role of the study reservoir. The example application results in the upper Yangtze River show that optimized joint operation of the multi-reservoir system, on average, reduces the peak flood flow at the flood control point by 1108 m³/s, increases the peak reduction rate by 1.8%, and decreases the flood volume by 5.9 billion m³. The study reservoir makes a notable contribution to flood control within the multi-reservoir system, with an average peak reduction contribution of 5.4%, an average flood retention contribution of 13.3%, and an average flood retention coordination rate of 54.3% for the downstream remote reservoir.