Abstract: To complete the inspection of the X-axis positioning accuracy of the inclined-bed CNC lathe more smoothly, we introduce several laser interferometer optical path adjustment methods by summarizing a lot of working experience and clarifying the principle and steps of using angle mirror with laser interferometer and other mirror sets to complete the optical path adjustment. The method makes good use of the characteristics of the adjustment accessories equipped with the interferometer and solves the difficult problem of adjusting the optical path collimation of the inclined axis.