Abstract: Cascade hydropower stations are connected in the basin and adjacent in space. The influence of the upstream projects under construction or completed on diversion and closure are reflected by the variation of flood characteristics during construction. As construction of cascade hydroelectric stations changes the original flood drainage channel and flood control as well as dynamic characteristics of construction diversion are different from construction case of single power station, flood has multiple attributes and uncertainty in time and space. In this article, main factors and contents are inducted and summarized about the diversion design, taking consideration of the regulation effect of upstream and downstream cascade reservoirs. Some main principles and matters need attention about diversion standards with the regulation effect of cascade hydropower stations are put forward.