Abstract: In order to improve the observability of strapdown inertial navigation system(SINS)in the process of initial alignment,a new initial alignment method is presented by changing the transform matrix of the SINS’modeling error when the azimuth axis rotated continuously.The new method improves the observability of SINS in the process of initial alignment,and meets the requirements of accuracy and time.The SINS’observability in this new method has been compared with the alignment based on the stationary and the traditional multiposition,and it deduced that the observability of the continuous rotation manner is highest.The simulation results show that the estimation accuracy of azimuth misalignment angle in the presented method is approximately 2 times higher than that of the two-position and three-position alignment,therefore the accuracy of initial attitude is improved.