Abstract: In this paper, to study the impact of pumped storage on hydro-thermal joint scheduling system, a new optimal economic dispatch model for hydro-thermal and pumped storage joint system is proposed, and it can be solved by using hybrid GAMS and branch-bound method. Simulation is carried out to verify the feasibility and validity of the model. The results show that this model can take advantage of hydro power resources, and relieve pressure on thermal power during peak period. In addition, according to characteristics of pumped-storage power generation, peak load shifting for thermal power unit can be realized to improve operation conditions of thermal power unit, to smooth thermal power output curves, to reduce emissions of pollution gases, and to ultimately improve the stability, economy and environmental protection of entire power system. At the same time, it also has certain reference for studying the impact of energy storage on the power system.