Hydrological connectivity of rivers and lakes is of great significance for maintaining water resources security and ecosystem stability. In this paper, based on the measured hydrological data of Xinjiangkou and Shadaoguan stations in Songzikou, Zhicheng station in the Yangtze River and the topographic data of the typical cross sections from 1960 to 2019, characteristics and causes of the water diversion change of Songzikou in the dry season were analyzed and discussed by the Mann-Kendall and the trend line methods. Then, the paper put forward the river management plan for the problem of the diversion of Songzikou River in the dry season. The results show that water discharge of Songzikou in the dry season mainly came from the west branch. During 1960-2019, runoff of the west branch changed from a downward trend to a significant upward trend before and after the impoundment operation of the Three Gorges Dam in the dry season, while the east branch was in a state of draught-up after the cutoff of the Lower Jingjiang River. The main causes of runoff variation are the cutoff of the Lower Jingjiang River, and the impoundment operation of the Gezhouba Dam and the Three Gorges Dam. The simulation results show that if the river bed elevation decrease about 1 m and 2.5 m respectively in the west-east branch of Songzikou, and the water diversion could reach or approach the water discharge level in the 1960s, which is helpful to alleviate the regional water resources, environmental and ecological problems.