This paper presents an analysis of the riverbed evolution trend of Chengtong reach of the Yangtze River in terms of the river facies relation, with the main focus on the change of the sectional area of typical section under the different discharge and sediment concentration. The result shows that when the sediment concentration decreases from 0.312 kg/m3 to 0.043 kg/m3, the sectional area of typical section increases 55%. At the same time, while the discharge of ebb tide increases from 10 000 m3/s to 100 000 m3/s, the sectional area increases nearly 7.7 times. These indicate that under the current status of continuous decrease of sediment concentration from the upstream, the occurrence of overall erosion in the Chengtong reach is highly possible in the future. In addition, the sectional area will increase also if the discharge from upstream increases.