Three Gorges (TG) cascade stations plays an important role in power system, which is a major power supply station burdened with trades between multi-provincial grids. Hydropower Scheduling Decision Support System (TGDSS) is developed to improve scientific and economy of reservoir operation. In order to increase comprehensive benefit of TG Project, the practical models of joint scheduling, peak regulation and operating mode in power market are designed to provide timely decision-making. Subsequently, the structure, function, model division and realizing methods are introduced in detail. The practice shows that TGDSS has greatly increased the cascade water utilization rate and promote resource optimal configuration.