Abstract: Aiming at prominent problems including severe data silos, low collaboration efficiency and insufficient risk control capacity in the full-process investment management of railway engineering, this paper designed a data-driven full-process investment management system for railway engineering. It illustrated the system architecture. Relying on technologies such as project control, data sharing and data link construction, the system realized functions covering investment budget estimation, plan management, contract management, statistical management, work measurement and pricing, as well as financial management, and supported full-process investment management throughout project approval decision-making, survey and design, engineering construction and completion acceptance. The system carried out pilot applications on multiple railway sections under the administration of Shenzhen Engineering Construction Headquarters of China Railway Guangzhou Group Co., Ltd. Application results show that the system effectively standardizes management procedures, streamlines information circulation, guarantees end-to-end connectivity of full investment data links, and realizes risk pre-control. It significantly improves the efficiency and refinement of investment management, and provides replicable and scalable solutions for the digital upgrading of railway engineering investment management.