Abstract: The paper aims at the problem that the positioning errors in the current inertial navigation system (INS) accumulate with the increase of the running time. The gravity aided navigation technology is proposed, and the dynamic base gravity sensor, real-time Marine gravity measurement of the moving base, gravity field map matching theory and matching algorithm as the core, and the related INS error model are introduced. The combined gravity /strapdown inertial navigation system (SINS) navigation method based on unscented kalman filter (UKF) is analyzed, which improves the accuracy of navigation and positioning.