Abstract: The rational expansion of passenger ro-ro transport ships in the Bohai Bay requires scientific guidance, ensuring the coordinated development and safety of cross-sea transportation. This study aims to clarify the development process of large-scale passenger ro-ro ships, considering market demand, enterprise operations, industry management, and other factors influencing supply and demand. Additionally, it systematically examines the layout characteristics of passenger ro-ro transportation routes and ports, as well as analyzes the structural distribution of passenger ro-ro enterprises and ships' transport capacity. Furthermore, it identifies the demand orientation for the integrated development of ships, ports, and shipping. The calculation method of navigation infrastructure dimensions in the overall design specification for seaports is referenced, and a reverse engineering approach is employed to derive the calculation formula of ship type. By matching and adjusting the theoretical results and consolidating the values, four large-scale standard ship types for ro passenger ships in the Bohai Bay are proposed, including their main parameters such as overall length, molded width, full load draft, and gross tonnage. Finally, the applicability of the proposed large-scale ship types for 30 ro-ro passenger berths in the Bohai Bay is evaluated, providing technical support for guiding the standardization and serialization development of new interprovincial ro-ro passenger ships in the region, and enhancing the safety and security of ships' port operations and seaworthiness.