The high precision calibration of laser sensors in high-precision composite measuring machines is done. The calibration method of the optical axis perpendicular error angle by using the calibration block with double slopes with known base angles and the sine theorem is proposed. This method can avoid the errors from various directions caused by the non-perpendicular orientation between the optical axis of sensors and the worktable, which can effectively improve the measurement accuracy of this sensor and provide a basis for multisensor duplex measurement with higher accuracy.