The application of adaptive Kalman filter technique in inertial navigtion system is studied in this paper.In case of the noise statistic characteristic being unknown or not completely known,there would exist a large error in estimating state using conventional Kalman filter,even made the filter diverge. However,adaptive Kalman filter can,at the same time of estimating state,estimate the statistic characteristic of noise online using observation information.Therefore the design of the filter can be continuously improved and the obtained estimation using adaptive Kalman filter possessed higher accuracy compared with that of conventional Kalman filter.The paper gives the simulation of initial alignment,which adopted Sage Husa adaptive Kalman filter algorithm.The validity of the proposed means is proved by the simulation result.