The unfavorable water flow in the approach channel area of the Longtan hydropower station affects the access safety of ships. To improve the flow velocity of the upstream and downstream approach channels and the entrance area，this study optimizes the extension scheme of the navigation wall of the upstream and downstream approach channels. Specifically，we build a physical ship-lock rectification model of the Longtan hydropower station to study each typical working condition in the operation process. The following conclusions are drawn：1） When the flow rate of the upstream river channel is greater than 1 100 m3/s，and the ship lock is fully opened，the water flow conditions in the entrance area of the upstream approach channel still cannot meet the requirements of the specification. 2） After the downstream approach channel changes the main navigation wall from permeable to impermeable，the flow conditions of the approach channel and the entrance area can meet the requirements of the specification.