Railways have become the main transportation artery in our country, and many railway tunnels are distributed because of the diversity of geographical conditions. There are many structural safety monitoring methods for railway tunnels. However, traditional monitoring methods have certain limitations. Based on the current research which focuses on optical sensing, the optical video replacement technology with excellent accuracy and high economic feasibility is organically combined with fiber grating sensing technology, and the optical sensing is applied to the safety monitoring of railway tunnels during operation. Through the analysis of monitoring data in static and traffic conditions, combined with the simulation model, the application of optical sensing in railway tunnel monitoring during operation is preliminarily discussed to provide a reference for related engineering technologies.