The second-line ship lock of the Xiangqi Junction on the Xiangjiang River is an additional second-line ship lock on the shore of existing buildings，resulting in a curved connection between the approach channel of the second-line ship lock and the main channel. Due to the limitation of the approach channel of the first-line ship lock and the short wheelbase between the first-line ship lock and the second-line ship lock，the navigable flow conditions in the upstream and downstream entrance areas and connecting sections of the proposed second-line ship lock are relatively complicated. Therefore，relying on the expansion project of the second-line ship lock of the Xiangqi Junction，we conduct a 1:100 fixed-bed physical model test on flow to analyze the navigable flow conditions at the entrance area of the downstream approach channel of ship locks. A series of experimental studies are carried out on the optimization of the opening method of the sluice lock，the optimization of the dike of the downstream approach channel of the second-line ship lock，the optimization of the embankment on the right bank downstream of the power station，and the local dredging of the river channel downstream of the outlet of the power station. Moreover，optimization measures are proposed to improve the navigable flow conditions.