Abstract: Fengman and Baishan reservoirs are important flood control projects on the second Songhua River. Due to the reconstruction of the Fengman Dam and the extension of the flood series, the key flood control characteristics of Fengman Reservoir and the design flood results of Fengman and Baishan reservoirs have undergone important changes. Affected the effectiveness of the original reservoir flood regulation plan, it is urgent to re-formulate the flood joint regulation plan based on the new engineering and data conditions. The research adopts the model of combining two reservoirs into one reservoir, and analyzes the flood control capacity of the reservoirs based on the new design flood results. The research results show that:(1) The total flood regulation capacity of Fengman and Baishan can support the two reservoirs to complete all flood control tasks;(2) When encountering a single-peak flood, all flood control tasks can be completed by Fengman Reservoir alone, without the use of Baishan Reservoir to retain floods;(3) When encountering a double-peak flood of more than 100 years, the flood control ability of a single reservoir in Fengman Reservoir can no longer support it to complete all flood control tasks, and it needs the assistance of Baishan Reservoir.