Strapdown inertial navigation system (SINS) determines all motion parameters such as position, velocity, and attitude of the carrier through integral operation by using measurement information and initial system parameter of inertial components. Neither relying on any outside information during operation nor radiating energy outside, it is a completely autonomous navigation system. However, since various errors of navigation system have also been subject to integral operation, navigation calculation error of SINS accumulates continuously with the time, and oscillates and diverges constantly. Therefore, it is a must to understand error characteristics of SINS and conduct necessary system modeling, calibration, and compensation.