Abstract: To ensure the information security of the railway enterprise management information system construction project, this paper focused on the ISO27001 information security management system and carried out network security mechanism construction from three aspects: network security system, information construction, and network security technology. The paper improved the network security management system, formulated the information construction management mechanism, and established a network security technology linkage mechanism. The network security mechanism based on ISO27001 information security management system has been applied in the construction project of enterprise management information system, which effectively enhances the proactive defense capability of enterprise management information system, meets the requirements of railway enterprise network security management, and provides reference for railway enterprise network security work.