A laser micro displacement measuring system for measuring dynamic micro displacement is introduced.This system is based on Doppler effect and the He Ne laser is taken as its light source.The system deploies the frequency conversion for telling direction,high speed dynamic acquisition system for CCD vedio signal,micro computer processing system and interference image handling software etc.Comparing with the traditional measuring method,its accuracy,sensitivity and stability are more raised and its error is more decreased.The full automatic measurement of micro displacement is realized.