In NC machining , because the verticality error of the optical axis of the laser probe cannot be accurately obtained , in order to solve this problem , a calibration method for the optical axis perpendicularity error of the laser probe in NC machining is proposed. By building a mathematical model , the reference plane of the optical axis of the laser probe is determined , and the ideal perpendicularity of the optical axis of the laser probe is calculated. The binary denoising operation is performed on the optical axis image of the laser probe , and expand its boundary. The perpendic- ularity characteristic information of the optical axis of the laser probe is extracted by Harris operator , and the perpen- dicularity between the optical axis and the object surface is adjusted to achieve the calibration of the perpendicularity error of the optical axis of the laser probe. The experimental results show that the proposed method has high accuracy in calibrating the optical axis perpendicularity error of the laser probe , and the error value is kept at - 0. 5 ~ 0. 5 mm , indicating that the proposed method has good performance.