For the large cascaded hydropower stations, an electricity pricing mechanism of cascade hydropower stations on large basins is proposed. The main idea is that the electricity generated by different hydropower stations on the same river can be sold to the Grid Corporation with the same price. Using five hydropower stations on the middle and lower reaches of some river in China's south-western region as a case, the pricing methods based on the Operation-period pricing method are studied. The changes of hydropower stations' earnings are analyzed through the cascade hydropower stations optimal scheduling model and simulation analysis. The results show that the mechanism is conducive to hydropower development and the comprehensive utilization of water resources, which provides an alternative of electricity market reform strategy for the national energy departments.