The study region of this paper was the typical segments of hydraulic engineering disturbance from Hongjiadu Dam hydropower station to Wujiangdu hydropower station in the middle and downstream of Wujiangdu Dam. The MIKE11 model was used to simulate and calculate monthly average runoff and water levels of damsite over the three periods, i.e., before construction of Wujiangdu hydropower station, during the single-reservoir operation after construction of Wujiangdu hydropower station, and joint control with the upstream and downstream hydropower stations after its construction, and the cumulative effects of cascade hydropower development of Wujiang main stream on hydrological regimes. The results showed that, the hydropower station construction and joint operation made the discharge homogeneously and water level increase after the implementation of cascade hydropower development plan. The homogenizing effect reduced the flood flow and compensated the dry period flow. The increase of the water level increased the capacity of the reservoir area. The control of cascade hydropower had some ecological impacts on ecological water requirement of egg reproduction of downstream fishes.