Heading error of Strapdown inertial navigation system (INS) may be enlarged in some complicated road and vehicle conditions when maneuvering long time.An integrated navigation algorithm based on single INS (SINS) integrated navigation algorithm frame was presented.Integrated navigation was achieved through Kalman filter with 21 error states of the inertial measurement unit/distance transfer unit (IMU/DTU),which selected the difference between the displacement increment obtained respectively from the INS and the DTUas the observation term.Most errors of IMU/DTU integrated navigation system was canceled automatically by way of rotation and Kalman filter,which integrated information from the INS and the DTU.Precise position information and attitude information could be output without special conditions for marching vehicles.Some simulation experiments and vehicular tests were executed,which showed that the algorithm was able to achieve precise heading(attitude) and position.Potential accuracy was discovered.Rapid response capability,environmental adaptability and usability were improved greatly.