Based on the definition of modularity and the design ideas and methods of modularity, the module function analysis and decomposition of the ro-ro channel system, the construction of modular equipment library, and the module combination application are proposed respectively. According to the strength requirements of the ro-ro channel system in GJB, the modular design structure size related to the gangplank and end hinge of the ro-ro system is given. In the interface system, the modular design of the wire rope system and lashing system is analyzed, and the relevant design scheme can be given after the structure size of the ro-ro system is determined.