Abstract: As a further extension of the Internet, the Internet of Things(IoT) has deployed a large number of monitoring and control equipment or edge computing nodes on the site, which makes the network information security boundary more fuzzy, and also puts forward higher requirements for the security protection strategy of the railway IoT application system. The paper summarized the security characteristics of the railway IoT business application, analyzed the security challenges of the railway IoT from the dimensions of equipment, network, data and application, put forward security countermeasures for building the railway IoT security reference framework and full lifecycle security management model, discussed new technologies to ensure the security of the railway IoT. The research on the security of the railway IoT system in this paper can provide reference for improving and enhancing the railway network security and information system.