Abstract: In order to understand the safety status of long-distance oil/gas pipelines crossing tunnels when deformation and displacement take place, the safety monitoring was performed for a gas pipeline crossing tunnel in Shandong Province. This paper presents the possible causes and identification approaches of displacement and deformation of the pipeline crossing tunnel, the composition and principle of automatic monitoring system in tunnel, the recommended optimal program to install the monitoring system, as well as the method and experience of data analysis. Some experience in selection and installation of monitoring system is illustrated. The research results indicate that large adaptive deformation will occur at the initial stage when the pipeline crossing tunnel is put into operation; therefore, the band binding shall be avoided where the curvature of pipeline is large. When the pipeline suffers from large displacement and deformation, the proposed monitoring approach can be used for safety analysis, so as to obtain the safety status of pipeline crossing tunnel.