Abstract: The framework of optimization,fitting,re-optimization and simulation approach for deriving the optimal operating rules for cascade reservoirs is proposed and developed in this paper. Fmstly,the optimal data set is obtained by using the deterministic dynamic programming method to solve the optimization rmdel. Secondly,the operating rules are established by using the statistical analysis of the optimal data set. Thirdly,the operating rules are refined by using the simulation based optimization method. Finally,the operating rules are verified by using the synthetic inflow generated based on the stochastic hydrology. The Qingjiang cascade hydropower plants are selected as the case study.It is shown that the proposed method works well and can improve the hydropower generation greatly.