In the long river section between the two dams of Shihutang junction and Xiajiang junction in Ganjiang River，due to the protection of the reservoir area of Xiajiang junction，the actual operating water level on the dam of the junction is far lower than the designed operating water level in recent years，resulting in the overall reduction of the water level in the river section between the two dams and leading to many problems，such as the failure of normal use of most wading projects between the two dams due to the deviation of the designed water level selection at the design stage.Using the one-dimensional numerical simulation method of the long river section，this paper calculates the river water surface profile under the combination of the multi-level characteristic flow in the flood and dry season and the actual operating water level in front of the dam corresponding to Xiajiang junction according to the actual operation scheme of Xiajiang junction.Then，it calculates and analyzes the water level along the river section between the two dams and the channel gradient and selects the upper and lower envelope lines of each group of backwater curves as the reference water level for the design of the river section at this stage.The research results of this project can provide hydrological characteristics reference data for the design of wading projects in the studied river section.