The Cao'e River estuary ship lock connects the inland and offshore rivers.The hydrological conditions of the river section are complex, the riverbed situation is varied, and the buildings are dense.The operation of the ship lock is affected by strong tides.These lead to crossflow and backflow in the entrance and approach channel, which are prone to exceeding the standard.The layout plan of the ship lock is particularly crucial for improving water flow conditions.Based on the measured terrain data of the Qiantang River, a two-dimensional tidal mathematical model is established to compare three different layout types of ship lock design.The results show that Scheme one in which the approach channel outlet is arranged in the connecting lines on both sides of the outlet of Cao'e River Gate is better, and it has little impact on the flow velocity and flow pattern of the surrounding waters, including the Cao'e River Gate, Jiashao Bridge, and the offshore deep troughs of the project section.The navigation flow conditions of this scheme are better, and the navigation guarantee rate of the approach channel and entrance area is relatively high.Therefore, it is the recommended scheme.The semi empirical and semi theoretical formula is used to calculate the impact of riverbed erosion and deposition in the recommended scheme.The results show that the impact of the recommended scheme can be basically controlled within the Cao'e River estuary area.