Aiming at the large calibration error of the existing calibration methods and the poor observability of some parameters, two systematic calibration schemes are designed this paper according to the different observed quantities. Based on the error propagation model, the systematic calibration model of Strapdown Inertial Navigation System is derived again, and the 24-dimensional large system calibration model with “velocity error” as the observed quantity and the 12-dimensional reduction calibration model with “velocity error + attitude error” as the observed quantity are established respectively, and then different calibration paths are designed. The simulation results show that the two calibration methods have high calibration precision and complementary advantages, and can be used in different calibration environments.