The navigation flow conditions at the entrance of the approach channel affected by the upstream curve river course are very complex.In this paper，a navigation hydraulic model test is carried out based on a water conservancy project to explore the function of connecting the approach channel with a bottom-permeable separation levee，and the distribution characteristics of flow velocity at the entrance of the approach channel under different lengths of separation levee are compared and analyzed.The results show that the separation levee can effectively reduce the velocity gradient between the entrance of the approach channel and the river mainstream，and improve the navigation flow conditions.With the increase of the length of the separation levee，the maximum longitudinal velocity and transverse velocity at the entrance of the approach channel tend to decrease.The length of the bottom-permeable separation levee should be reasonably set by comprehensively considering the flow conditions，cost，and other factors.