Abstract: The performance of conventional Inertial Navigation System (INS) augmentation approach is subject to the accuracy of external aiding sensors, for which the accumulated INS error couldn't be fully eliminated. A novel INS correction method is proposed, which take the advantage of high stability of INS solution in short-term. INS error was estimated by data fusion of INS output without aiding and external sensor measurements, and it was then applied in INS augmentation. The location accuracy of INS was enhanced in comparison with sensor accuracy. A representative scenario, augmenting INS using the radar seeker measurement during missile midcourse flight, was then discussed to help explain this novel aiding method using data fusion method. Lastly, the validity of proposed approach in INS aiding was then tested by simulation.