Abstract: The changing of runoff in the river basin or upstream or the inaccuracy of inflow forecasts may result in a mismatch between the hydropower generation based on actual inflow and the planned load of the grid based on deterministic inflow forecasts. In such circumstances, if the hydropower plants still follow their original plan in operation, they will be likely to violate water level constraint or bring about a mass of surplus water. To solve these problems, a real-time load-adjusting method of cascade hydropower plants considering inflow-changing conditions is presented herein. Under inflow increasing, this method can guide the plants to generate more electricity by reducing surplus water release and be able to adjust thermal power output to absorb the spare hydroelectric power; under inflow decreasing, it can reasonably redistribute the load among plants considering the effect of energy storage in the cascade reservoirs and redeploy the thermal power to offset the deficit in hydropower generation by the grid load demands. Its feasibility and effectiveness was demonstrated in a case study of a hydroplant cascade on the Central China Power Grid, including the plants at Sanbanxi, Baishi, Tuokou and Wuqiangxi. The results show that our new method can effectively reduce the adverse impact of hydrological regime changing on the dispatches for upcoming periods. And the method can work out a plan adjustment that meets the requirements of hydropower plant operation and ensures the safety and stability of power grids.