When the downstream navigable entrance area is located in a curved narrow channel section，the water depth of the river is relatively shallow and the navigational flow conditions are very complicated，which is not conducive to navigation. Relying on the second-line ship lock project of Jingnan junction，a series of experimental studies have been carried out on the navigational flow conditions of the multi-lane lock in the curved narrow channel using a 1：100 overall physical model. The results show that：1）The original junction layout plan has defects. The water flow conditions at the entrance of the downstream approach channel are easily affected by the water flow at the top of the bend，and the narrow cross-section leads to larger flow velocity. 2）At the same time，the separation dike’s elevation is so low that it will cause water flow to overturn the separation dike and produce chaotic flow. The following improvement measures are proposed：1）The elevation of the upstream separation dike should be increased to 33.46 m and the elevation of the downstream separation dike should be increased to 32.58 m. 2） It is recommended to add a partition wall，smoothen the shoreline，and excavate the riverbed. The research plan provides technical support for improving the navigable flow conditions of the second-line ship lock project of the Jingnan junction.