Abstract:A new fitting method based on both the position and the velocity of satellite is presented in this paper and a fitting formula is deduced. Then, the fitting and the extrapolating accuracy are compared between conventional position based fitting method and the new positionvelocity based fitting method. Compared with conventional fitting method, the new fitting method shows a significant improvement in velocity accuracy, with a slight improvement in position accuracy. Besides, the new method’s advantage is more obvious when the fitting epoch is few.