Abstract: The lower reaches of the Yangtze River is broad,and dominated by branching channels. Normally,there is a single section connection between two branching channels,playing a key role in fluvial processes. Taking the single curve Longtan Waterway as an example,this paper analyzes the changes of shoals,typical cross sections and the stability of the river and the influence of water and sediment condition on fluvial characteristics after impoundment of the Three Gorges Reservoir（TGR）is discussed. Results show that,before and after the impoundment of TGR,the bank line is basically stable under the action of river regulation engineering,and the cross-sections maintain narrow and deep. Compared with the wide branch section,the total amount of scour and deposition of Longtan Waterway after the Three Gorges impoundment is getting relatively small. The river bed changes mainly occur below the-20 m elevation and around the shoal areas. Generally speaking,after the Three Gorges impoundment,the evolution of Longtan Waterway is mainly affected by the sharp decrease in sediment quantity. The adjustment of the river bed is slow,and the effect of the flood year is relatively large. However,the local scour caused by the big water year is difficult to recover in general years. In the future,it is still necessary to pay attention to the scour changes of the low beach of Xinglongzhou.