Abstract: Based on the Michelson interferometer，this paper introduces a new experiment method to measure the micro-displacement. The incident and reflected light are multiply reflected by adding the parallel plane mirror group in the Michelson optical path. When the distance between the parallel plane mirrors presents a small change，the optical path difference of the two reflected light beams will be amplified such that the micro-displacement can　be calculated according to the measured change of interference fringe. The design of experiment optical path as well as the corresponding experimental verification are achieved. The measurement accuracy is greatly improved by this proposed method comparing with the traditional Michelson experimental facility.

Key words: Michelson interference, optical - path amplification, micro - displacement, parallel plane mirror group