The Cherenkov Telescope was designed to study high-energy cosmic ray. The Large Telescopes and Medium Telescopes in the Cherenkov Telescope Array are usually equipped with Photo multiplier Tubes or Silicon Detectors. These detectors are used to detect the Cherenkov light produced by the interaction of gamma rays with the atmosphere. The mirror system and the PMT are supported from each other by rigid mounts. Their relative position is critical to ensure high angular resolution. Laser interferometric methods are used to measure changes in the position of the PMT detector, which may be affected by gravity, temperature, wind, or other factors, and can also be used to detect the shape of the telescope mirror. More accurate data can be obtained by monitoring small displacements in real time or irregularly. This paper focuses on laser interferometry remote measurement of small displacements and high-precision displacement signal processing. The present study establishes a laser interferometry system and collects interference signals, which indicate distance consistency and validate the feasibility of the system.