In the context of the double-lane ship locks sharing approach channel project,unsteady flow is prone to occur in the approach channel during lock discharge,causing turbulence in the flow field inside the approach channel,seriously affecting the safety of ship navigation and docking in the approach channel.Taking Mujing ship lock as an example,based on the RNG k-ε turbulent flow model,the navigation hydraulic characteristics of the approach channel are numerically simulated,and the unsteady navigation conditions inside the second-lane lock and the approach channel are analyzed during the discharge of the first-lane ship lock.The results show that when both sides of the first-lane ship lock release water simultaneously,the flow velocity in the approach channel does not meet the requirements of ship navigation and docking,and the formation of reflux,oblique and transverse flow patterns at the front of the separation dike of the second-lane ship lock affects the safety of ships entering and exiting the second-lane ship lock.After adopting the recommended side discharge method,the flow pattern in the approach channel has been improved,and the navigation flow conditions meet the requirements of safe navigation.The research results can provide a solution for the discharge method of double-lane ship locks.