Abstract: To address the issues of fragmented ticketing and inefficient transfers in cross-sea intermodal passenger transport (referred to as intermodal transport), this paper designed and implemented a railway-waterway intermodal transport service system based on the China railway 12306 Internet ticketing and reservation system (12306 for short). Aiming to achieve "one ticket for the whole journey and one certificate for smooth travel", the paper integrated railway, highway and ferry resources, and focused on elaborating the system architecture, core functions and key technologies. Specifically, the system realized multi-standard ticketing integration through a multi-level order structure and a unified coding system, developed an all-in-one ticket checking terminal to support integrated verification across different transportation modes, and constructed a highly available service system to guarantee stable business operation. Pilot application results indicate that the system significantly improves the efficiency of passenger intermodal transport and enhances travelers' experience, provides a practical paradigm for national passenger intermodal transport services and strongly supports the high-quality development of the comprehensive transportation system.