Abstract: To address the urgent demand for the full-life-cycle digital delivery of simply supported girder bridges on high-speed railways, this paper designed a digital engineering-based completion and delivery system for simply supported girder bridges. By establishing a mapping mechanism between Engineering Breakdown Structure (EBS) codes and Work Breakdown Structure (WBS), the paper realized multi-stage data integration and correlation across design, construction, operation and maintenance phases. On the basis of EBS, WBS and lightweight Building Information Modeling (BIM) data, and combined with distributed microservices and cloud rendering technologies, the system achieved cross-terminal and low-latency digital twin interaction. The system was piloted on the Pingwu No.2 Extra-large Bridge of the Sichuan section of the Chengdu-Chongqing Middle Line High-speed Railway. The application realized lossless transmission of design data, fully digital control of the construction process, and intelligent collection of operation and maintenance archives, which verified its technical feasibility in complex engineering scenarios. This system provides a valuable reference for the digital delivery management of railway engineering throughout its full life cycle.