Abstract: The equivalent load duration curve is used in traditional equivalent energy function method to simulate stochastic production, which loses time information, and is not suitable for operation simulation of pumped storage station.Then the available capacity distribution cumulant method is put forward to optimized dispatching of pumped storage station.At first, the scheduling model is built based on economy and reliability objective function,and load curve decomposition is used for peak load shifting of load curve. Then the generation amount of generation units and reliability index are calculated on the sequential load curve by applying the available capacity distribution cumulant method. The advantage is that the tail information of available capacity distribution curve can be avoided, and the uncertainty of load forecasting and outage rate of pumped storage station is also considered. The example results show that the proposed method can be applied to the optimized dispatching of pumped storage station.