It is an innovative measure for improving the inland shipping capacity by preserving the outdated ship lock as an approach channel in extension and reconstruction projects including Fuchunjiang ship lock.The results show that the water level of the outdated lock chamber will decrease rapidly during water filling for the new chamber due to the smaller wetted area at the entrance of the outdated navigation lock.Consequently,the concentrated hydraulic drop formed commonly at the doorsill of the outdated navigation lock is 7.15 m.Under the prerequisite of satisfying the requirement of the filling time and considering characteristics including the hoisting capacity,vibration,cavitation and over filling (emptying).We propose the optimized mode of the conveyance water locks,i.e.,inermittent opening combined with closing in dynamic water,which makes the concentrated hydraulic drop at the doorsill of the outdated navigation lock reduced to 0.5 m.The flow regime in the approach channel is improved with the optimized mode.