Based on the overall relocation and protection project of “Yangtze River Estuary II” ancient ship in 2022, aimed at the failure of the decompression drainage behind the dock wall of No. 1 Shipyard, the short-term working conditions of the salvage ship in and out of the dock and the permanent working conditions in the later period are simulated. The displacement and stress of the dock wall and pile foundation are analyzed and calculated. It is found that when Dock No. 1 is re-used, the load increment mainly comes from the groundwater pressure behind the dock wall that cannot be drained. The calculation shows that the original pile foundation structure of the dock wall has a reasonable design force, and the installation of a decompression drainage system can greatly reduce the water pressure behind the dock wall. In the short-term working conditions of the salvage ship entering and leaving the dock, the water pressure behind the newly added wall is small, and the displacement and bearing capacity of the pile foundation are not exceeded. In the long-term working condition, if the decompression drainage system completely fails and the new water pressure behind the wall is large, the uplift bearing capacity of the inclined pile may exceed the limit. Therefore, in order to ensure the long-term safety and durability of the dock and reduce the impact on the surrounding environment, reasonable measures should be taken to ensure that the drainage channel behind the dock wall is smooth and the groundwater level is maintained below the bottom of the lower beam in combination with the situation of dock reuse in the future.