Abstract：On the basis of detailed analysis of the principle and steps of zero-difference kinematic precise orbit determination, we adopt the smooth Kalman filtering algorithm, and use self-developed precise orbit determination software for zero-difference kinematic precise orbit determination of GRACE-FO satellite. The results show that, compared with the official scientific orbits, the smooth Kalman filtering can not only improve the accuracy of orbit determination at the beginning stage, but also improve the accuracy of orbit determination on the whole. The corresponding orbit residuals of GRACE-FO C and GRACE-FO D satellites are 2-4 cm and 3-5 cm, respectively.
