The water storage operation of the lower Jinsha River terrace reservoirs has an obvious impact on the water and sand conditions in the Three Gorges Reservoir area,which in turn causes changes in the navigation channel conditions.Based on the measured water and sand data,this paper analyzes the impact of the lower Jinsha River gradient reservoirs on the water and sand conditions of the Three Gorges reservoir during waning period.The results show that from January to May 2015,the discharge flow of Xiangjiaba increased by 37% on average,and the discharge at Zhutuo station and Cuntan station also increased by 34% and 26%.The sand transport amount at Xiangjiaba station has decreased by about 98%,from over 58% of the sand amount at Cuntan station to 1%-5%.The change of water and sediment conditions is conducive to improving the channel conditions in the Three Gorges Reservoir area.In particular,the minimum maintenance depth of the channel in the lower reaches of Chaotianmen reservoir increases from 2.7 m in January to April to 2.9 m in December,while the channel conditions in the lower reaches of Chaotianmen are less affected by the discharge flow rate of Xiangjiaba.