Abstract: The strapdown inertial navigation system is generally used for photoelectric target calibration. The inertial navigation axis should be characterized by the photoelectric auto-collimation system for the measurement of the equipment axis. The consistency between the axis characterized by the photoelectric auto-collimation system and the inertial navigation axis is an important factor affecting the target calibration accuracy. In order to improve the measurement accuracy and efficiency of the photoelectric target calibration system, a photoelectric characterization and calibration method of the inertial navigation axis was proposed. This method was based on the analysis of the relationship between the deviation and consistency of the measurement results, and the angle deviation value between the auto-collimation system optical axis and the inertial navigation axis was obtained by fitting the experimental data, which was used for the system correction, so as to realize the high-precision calibration. Through the test, by combining the traditional optical machine correction method with the photoelectric calibration method, the calibration efficiency of the system could be greatly improved, and the consistency accuracy between the inertial navigation axis and the optical axis was less than 15″ at the same time. The experimental results show that compared with the traditional optical machine correction method by the traditional optical flat-crystal, the proposed method has higher characterization accuracy and calibration accuracy, which is suitable for high-precision inertial measurement system.