Zhaoxian junction is located in the bend section of mountainous rivers. The upstream approach channel is in the main channel of the convex bank，and the entrance area of the downstream approach channel is on the concave bank. The entrance area and the connecting section have serious adverse hydraulic phenomena such as lateral flow velocity，backflow，and water surface boil and flow vortex，which are difficult to satisfy the requirements of navigation. This study employs the overall physical model test on a scale of 1：80 to study the main reasons for the formation of adverse flow conditions in the upstream and downstream channels. We effectively reduce the velocity of cross-flow，lateral flow，and backflow by taking comprehensive measures such as adjusting the operation mode of the junction and dredging local downstream channels and make all hydraulic indicators up to specifications. As a result，flow conditions in both the upstream and downstream approach channels and the entrance area are greatly improved，which can ensure the safety of ships passing through the lock. The research results can provide a reference for related junction projects.