At present,there are some problems in the in-motion coarse alignment methods of land inertial navigation systems,such as signal masking when assisted by GPS and being limited by maneuvering route constraints when assisted by odometer.In order to solve these problems,a in-motion coarse alignment algorithm of SINS based on LiDAR SLAM is proposed.The updating algorithm of the attitude matrix based on the observed vector of velocity of LiDAR SLAM system is derived.By using the double vector attitude determination method based on REQUEST,the initial constant attitude matrix Cnb(0)is obtained,and the coarse alignment and position navigation are completed.In laboratory experiments with unmanned vehicle,the alignment error of the proposed method is reduced by about 56%compared with the odometer assisted method.Meanwhile the comprehensive experimental results of cooperation with other institutions show that the azimuth Angle error at the final moment is-0.0088° when the coarse alignment takes 250 s,achieving a rough alignment accuracy of 1 mil within 5 minutes,which is higher than that of the odometer assisted method under the same conditions.The proposed algorithm can effectively realize the in-motion coarse alignment of the inertial navigation system with the assistance of LiDAR SLAM that has a fast convergence rate.