Abstract: This paper firstly introduced the typical overall architecture of IT Integrated Operation and Maintenance Management (ITOM) System, and the relationship between ITOM System and CMDB Subsystem, explained the basic ideas about building Railway ITOM System and its CMDB Subsystem, described the design proposal and implementation of Railway CMDB Subsystem in detail, summarized the current construction achievements of Railway CMDB Subsystem and gave an outlook of its future development.