Abstract: The suspended sediment in the lower reach of Jingjiang River was getting less and less after the operation of Three Gorges Reservoir, resulting in the bed evolution change. The bed evolution of Jingjiang River is both the result and the reason of suspended sediment reduction. Based on the data of measured flow discharge and suspended sediment concentration of hydrological stations from 1992 to 2017 in Jingjiang River, the relationship between flow discharge and suspended sediment concentration was analyzed. The variation of water and suspended sediment relationship before and after the operation of Three Gorges Reservoir was studied. The evolution amount of Jingjiang River was calculated by sediment-transport balance method, and the strongest erosion discharges in different reaches were put forward.