Abstract: In the daily operation of the Three Gorges cascade hydroelectric power stations, working out the power generation program of each cascade under given total water consumption of two plants and optimizing the load distribution between two plants under given total load in order to get maximum benefit are two fundamental modes. Aiming at these two modes, a mathematics model is established based on various restraint conditions of cascade hydropower stations and their corresponding algorithms are given. Considering the affecting factors such as variable heads and time-delay of flow between two dams, the synthetic improved dynamic programming (DP) algorithm is applied to solve the optimization problems. Simulation study shows that the model and algorithm can solve the problems of optimal daily operation of Three Gorges cascade hydropower stations, and the results are satisfactory. Finally, The real-time optimization is discussed.