Aiming at the problem that gantry crane hoisting and sliding closure are not conducive to the fast and accurate docking of ship sections, and increasing the dock closure and crane occupation time, taken the closure of a cylindrical Floating Production Storage and Offloading (FPSO) in the dock as an example, the 3D regulator is arranged at the bottom of the dock, the accuracy measurement and carrying simulation are carried out with the help of total station and data measurement software, and the closure scheme of the bottom section of the cylindrical FPSO is optimized, so as to realize the accurate closure and docking of the sections in the dock and shorten the shipbuilding period.