Abstract: To address the data island problem caused by physical isolation between railway internal and external networks, as well as the drawbacks of traditional file exchange methods including low efficiency, poor security and incompatibility with large-capacity file transmission, this paper developed a file storage and secure exchange system for railway internal and external networks. The system adopted a microservice architecture. It constructed a horizontally scalable storage framework based on distributed storage technology, and realized core functions such as multi-mode file uploading, secure data ferry and shared collaboration by adopting key technologies including a hybrid access control model, multi-engine virus scanning and high-efficiency storage optimization. Practical application results indicate that the system achieves secure and efficient exchange of large-capacity files across railway internal and external networks. It remarkably improves the efficiency of railway data management and collaborative office work, cuts storage costs, guarantees the security of data circulation, and offers references for railway informatization construction and data security protection.