Abstract: Exploring the evolution situation of river-lake connected channel is an important link for assessing the impact of major human activities on the river-lake relationship. This paper takes the Songzikou outlet, a river-lake connected channel of Dongting Lake as the research object. The long-term water level-discharge relationship curves of Songzikou outlet were established to analyze the change characteristics of channel erosion and deposition. The reliability of the results is verified by the measured cross-section data. At the same time, the driving factors of channel erosion and deposition changes in Songzikou outlet were analyzed. The results show that the water level-discharge curve method is consistent with the measured cross-sectional topographic data. The decrease of water level under the same discharge corresponds to the channel erosion in this period, and the rise of the water level under the same discharge corresponds to the channel deposition in songzikou outlet. The main driving factors of channel erosion and deposition are different in different periods at Songzikou outlet. From 1968 to 1981, the main factor was the channel planform change caused by the river bend cutoffs of the lower Jingjiang River. From 1981 to 2003, the channel deposition was mainly caused by the channel erosion at the upper Jingjiang River due to the operation of Gezhouba Dam. During the period of 2003-2018, the channel erosion was mainly caused by the sharp change in the proportion of water and sediment due to the operation of the Three Gorges Dam.