Abstract: In the flood season of 2020,there was a long-lasting and wide-ranging heavy rainfall process in the Changjiang River Basin,which was only less than flood in 1954 and 1998 flood since 1949. We analyzed the scouring and silting change characteristics of the main stream of the middle and lower reaches of the Changjiang River under the 2020 flood. The results showed that the increase of upstream sediment and discharge sediment of Three Gorges Reservoir led to the decrease of scouring in the reach of Yichang to Hukou,and at the same time the severe backwater effect at middle and lower reach also reduced the sediment transport ability of this reach. During the flood,the water level rose quickly in the middle and lower reach,leading to easy silting,however the water fell slowly after the flood,causing un-sufficient scouring of sediment in the reach. In the Hukou to Jiangyin reach near the estuary,the water gradient was large and with less sediment concentration,so the sediment transport was relative large. The research provides a basis and reference for further study on the change law of scouring and silting in the middle and lower reaches of the Changjiang River and the prediction of scouring and silting trend in the future.