Abstract: Two research goals had been accomplished in this paper. One was to realize the calibration of strapdown inertial navigation devices in higher precision on the test equipment with lower accuracy outside. The other was to implement the synchronization of the inertial measurement frame in the process of calibration, and to improve its dynamic navigation accuracy. Accordingly, through deeply analysis of the space relative position between the two inertial measurement frames, the orthogonalization of inertial measuring frame was realized, and its misalignment model was established. Thereby, the paper designed the systemic calibration filter, which was based on the crossing angle and the misalignment angle, and raised the systemic calibration scheme, in this paper formulated the disturbance resistance measures of systemic calibration and a test was carried out. The test results showed that this calibration method can systematically calibrate all parameters of a strapdown navigation system and improve its dynamic navigation accuracy more than three times.