The reservoirs(Xiluodu, Xiangjiaba, Zipingpu, Pubugou, and Tingzikou)in the upper Yangtze River were considered as the object of study. A nonlinear safety degree strategy for the joint flood control system of the multi-reservoirs in the upper Yangtze River was proposed, based on which a flood storage capacity optimization distribution model for multi-reservoirs was constructed and an in-depth discussion for the flood control effect of the nonlinear safety degree strategy was conducted. The results show that compared with linear safety degree strategy of multi-reservoirs, the flood control capacity of Xiluodu reservoir can be less consumed by increasing the usage of the flood control capacity in other reservoirs by the nonlinear strategy in the condition that the flood control effect of the downstream is not deteriorated. The application of the nonlinear safety degree strategy can relatively balance the flood storage capacity allocation of the reservoirs, make the reservoirs share the flood risk of the flood control areas, give full play to the flood control benefits of the reservoirs, and ensure the stable and safe operation of the multi-reservoir system.