The upper reaches the dam site of Laomukong Navigation-power project on Minjiang River is transformed from multi-branch to single channel.Meanwhile,the downstream flow control node is pre-excavated,causing deteriorated navigation flow conditions.Aiming at navigation issues like scattered flow and rapid shallow current,the navigation flow conditions of phase Ⅱ adjustment scheme in the first dry season are systematically studied via overall fixed-bed physical model tests.The test shows that after the 8 holes on the right side of the phase Ⅱ cofferdam in dry season are widened to 10 holes,the water level connection between the upstream and the lower part of the middle channel of the Sanjiang village diversion is significantly improved.At the same time,a spur training dam with a length of 530 m is built on the left side and downstream of the transition section under the dam,which can effectively improve the channel depth and smooth the flow,and increase the minimum navigation depth from 1.51 m to 1.94 m.After the implementation of the optimization scheme,the navigation flow conditions are obviously improved,the maximum navigation resistance coefficient is reduced from 1.05 to 0.69,and all navigation hydraulic indexes meet the limits of relevant design specifications.The research results can provide reference for the optimization of navigable water flow conditions in similar navigation-power junction projects.