Global climate change and human activities, have led to a significant rise in the occurrence and intensity of extreme hydrological events in the basin. To deal with this situation and ensure the security of the country’s water supply, the national water network project was proposed. The South-to-North Water Transfers Project served as the primary framework to achieve this objective. Since the implementation of the Eastern Route of the South-to-North Water Transfers Project, water security has been significantly improved. However, Dongping Lake, as an important node reservoir and the last stage of regulation reservoir of the Eastern Route of the South-to-North Water Transfers Project, was underutilized for a comprehensive reservoir.To enhance the water supply benefit of the second phase of the Eastern Route and the resilience of the water resources system to extreme events, a new scheme was proposed by the surplus storage capacity of Dongping Lake to regulate water inflow into the lake. First, the concept of surplus storage capacity was defined, and the value of surplus storage capacity and variation were analysed according to the parameters of discharge into the lake, water consumption around the lake and the evapotranspiration loss of Dongping Lake Reservoir. Second, based on the principle of reservoir water balance, sequential logic of multi-source joint dispatching decision and multi-objective optimisation, different regulation schemes of Dongping Lake were proposed for the second phase of the South-to-North Water Transfers Project. The optimal storage scheme of Dongping Lake was recommended by comparing the application effects of different implementation schemes according to the influence of the guarantee rate of water consumption around the lake, the water demand of Dongping Lake, the water inflow into Yellow Lake and the safety of engineering. The optimal storage scheme could provide a concrete reference for the actual operation and management of the Dongping Lake Reservoir. The results show that: the average monthly surplus storage capacity of Dongping Lake from 1956 to 2016 was 117 million m3. It is feasible to use the surplus storage capacity of Dongping Lake to transfer and store the incoming water from the Eastern Route when the incoming water from Dawen River is dry and the water level of Dongping Lake is low. The scheme to regulate the storage capacity of Dongping Lake was recommended by analysing the effects of different schemes on the guarantee rate of water consumption around the lake, the water demand of Dongping Lake, the water inflow into Yellow River and the safety of engineering. Although the scheme has little effect on reducing the amount of water transferred from the Eastern Route, it increased the storage capacity of the Eastern Route by 362 million m3.The scheme of Dongping Lake needs to be adjusted in order to adapt to the changes in the external environment and to realise the comprehensive functions in the new time period.The scheme of Dongping Lake storage capacity regulation could make full use of the storage capacity of Dongping Lake and increase the flexibility of Dongping Lake reservoir dispatch. At the same time, this regulation scheme improves the resilience of the reservoir to extreme hydrological events. This is of great significance in enhancing the benefits of comprehensive reservoir utilisation and ensuring the water security in the basin.