The navigation flow conditions at the entrance area of the upstream approach channel laid at the downstream of sharp turns are complex. In order to address this issue，this paper carries out a hydraulic model navigation test for a navigation-power project to compare and analyze the flow field distribution at the upstream entrance area under different flow rates and different angles between the separation levee and the guide wall. In addition，the paper explores the relationship between the flow conditions at the entrance area of the upstream approach channel and the angles between the separation levee and the guide wall. The results indicate that the separation levee can effectively reduce the flow velocity gradient in the upstream approach channel and the main channel，alleviate the squeezing and friction caused by the main flow on flows at the entrance area，and then slow the transverse flow and backflow velocities at the entrance area to eliminate flow patterns not conducive to navigation. Furthermore，there is a threshold value for the angle between the separation levee and the guide wall. Specifically，when the angle is smaller than this value，both the longitudinal and transverse flow velocities decrease as the angle increases. On the contrary，once the angle is larger than this value，a partial inflow of mainstream appears，and flow patterns at the entrance area get worse.