In order to meet the needs of offshore oil field development under the new situation, taken the HYSY 122 cylindrical Floating Production Storage and Offloading System (FPSO) as an example, the hull construction technology is discussed in dock interior layout analysis, hull section division scheme, hull section prefabrication and section closure, and hull pipeline installation and key equipment installation. The technology adopts the management mode of whole process precision control to ensure the installation precision of key equipment, reduce the operation amount of confined space in the general assembly stage, and greatly compress the project duration, which can provide technical reference for the development of subsequent similar projects.