The present invention discloses a method and a system for calculation of generation benefit of a pumped storage power station. The method comprises the steps of: calculating a pumped storage conversion efficiency in the next year; obtaining water pumping electric quantity data in a first preset time period and generating capacity data in a second preset time period; calculating predicted generating capacity of each month in the next year according to the conversion efficiency and the water pumping electric quantity data, and calculating predicted water pumping electric quantity of each month in the next year according to the conversion efficiency and the generating capacity data; calculating the pumped storage economic benefit according to the predicted water pumping electric quantity andthe predicted generating capacity; and calculating the benefit hump modulation of the pumped storage according to the predicted water pumping electric quantity and the predicted generating capacity. The embodiment of the invention further discloses a system for calculation of generation benefit of a pumped storage power station. The method and system can accurately calculate the generating capacity and the water pumping electric quantity of the pumped storage power station in each month in the next year and can predict the economic benefit and the benefit hump modulation of the pumped storagepower station.