Owing to the flow confluence at the mid-channel bar tail in the anabranching channel of mountain river,the oblique flow may cause the obstacle to navigation.In order to reveal the influence of the oblique flow on the safety of navigation,the MIKE 21 hydrodynamic model is used to analyze the hydrodynamic characteristics and engineering improvement effects of the confluence area before and after the channel regulation project based on the existing physical and ship model experiments of the Dafutan navigation and power hub in Yuanshui River,a tributary of the middle Yangtze River in China. The results show that during the dry season,the oblique flow of the navigation in the confluence area exceeds the standard due to the high flow velocity in the right channel and the angle within the route.The longitudinal dike or spur dam constructed at the bar tail can reduce the impact of the oblique flow. Nonetheless,given that a longitudinal dike or spur dam parallel to the route is arranged at the bar tail,the magnitude of the oblique flow and back flow of the route increases the range of oblique flow distribution and is still beyond the standard value.Combining various engineering measures such as adjusting the shipping route,dredging the shallow area of channel,deflecting the longitudinal dike,and the overall arrangement angle of the spur pier can ensure that navigation flow at the bar tail meets the requirements of the norm.