Abstract: To increase power output of hydropower plants, a staged operation chart is presented in this paper to better represent the output capabilities in different seasons. We elaborate a basic principle and drawing method of the staged chart, and determine the hydrologic year, high-flow season, and low-flow season of the study catchment. Then, an optimal operation model is developed to maximize the total power output of the cascaded hydropower plants. Finally, we test this chart method via a case study of the cascaded plants on the Datong River. Results show that the staged operation chart is better than the routine operation chart and could provide a new way for the operation of hydropower plants.