The error of the inertial navigation system increases with navigation time, and inertial sensor is the main factor affecting the system precision. The revolution modulating technology can greatly improve the system precision under the condition that the inertial sensor keeps its original precision, and it is the main method for improving long time navigation precision of the inertial navigation system. On the basis of the domestic standard platform inertial navigation system, in the paper, the system algorithm and the azimuth matrix loop were improved, the errors diverging with time caused by the horizontal inertial measure unit were modulated as the constant errors. These constant errors can be eliminated by damping, and the precision of the inertial navigation system will be improved. The result of the simulation and experiment shows that the system designed by the authors meets the desired destination and have a good practice value.