Abstract: Pumped storage demonstrates significant peak-shaving and valley-filling effects. While combined operations with nuclear power can stabilize the utilization hours of nuclear plants, they may also compress the generation space for renewable energy. To address this conflict, this paper explores the planning of "nuclear-pumped storage" combined operation from system benefits. First, the reasonable installation ratio is studied from two dimensions: output equivalence and economic benefits. On this basis, using an 8 760-hour production simulation, it obtains key data profiles such as system generation costs, renewable energy accommodation rates, and coal power generation volumes for different combined operation scales. Finally, based on the objective weights assigned to key indicators by the entropy weight method, it integrates multiple data into a comprehensive evaluation to accurately recommend the optimal combined operation scale. The results indicate that the established analysis method can meet the requirements for combined operation planning across multiple indicator dimensions; conducting combined operation at a reasonable scale can achieve optimal overall benefits under the constraints of key indicators.