Abstract: The protection system is one of the essential systems, which assures the safety of CARR. Its function relies on its high reliability. The research on the reliability of protection system was carried out in the paper, using the reliability analysis methods including failure modes and effects analysis （FMEA） and fault tree analysis (FTA), and the relevant model was built. The qualitative and quantitative analyses of the protection system were carried out, and the fault probability and minimal cut sets were obtained. The design of the protection system was verified. The results can lay the foundation for the system analysis and verification of other systems of CARR.