The dock extension project is an adaptive capital construction project in semi-tandem construction of large container ships. The great changes in design ship type of new dock occur, and the ship mass distribution and loading conditions are quite different from those of the old dock. Therefore, it is necessary to conduct a load redistribution and reinforcement of bottom plating of the old dock. With the large-scale trend of newly built ships, the completed old dock extension project provides necessary infrastructure for the long-term development of the shipyard, and the design and construction experience can be of certain reference function for similar projects.