Abstract: In order to economically and reasonably exploit the regulatory capacity of hydropower station reservoirs and facilitate the efficient integration of wind and solar resources, a model has been established based on the microeconomic principle of diminishing marginal returns during the production of products. This model considers the ability of hydropower station reservoirs as a variable factor, treating the efficient consumption of wind and solar resources as the "fixed factor ". The model aims at maximizing the benefits of hydro-wind-solar co-generation and can be solved to obtain optimized operation plans for hydropower station reservoirs to facilitate the economic consumption of wind and solar resources. The case analysis results demonstrate that, under certain conditions such as inflow, load demand, and reservoir operation status, the model effectively reflects the contribution of the hydropower station reservoir to the economic consumption of wind and solar resources and the benefits of hydro-wind-solar co-generation when participating in wind and solar output regulation. Optimized operation of hydropower station reservoirs involved in wind and solar output regulation under different scenarios is given. The model can provide reference values for fully leveraging the regulating capacity of hydropower station reservoirs and enhancing the benefits of hydro-wind-solar co-generation within the framework of ensuring the security of the power system.