Abstract:  Based on the 5-minute precision ephemeris of GPS satellites, this paper uses Lagrange polynomial interpolation with the type of sliding and nonsliding and Chebyshev polynomial fitting method to calculate the instantaneous coordinates of the satellites. The relationship between the precision of interpolation and interpolation order is determined, then the advantages and disadvantages of various methods are compared and analyzed. The results show that the interpolation algorithm with the type of sliding can suppress the oscillation and jumping anomaly near the endpoints in the Interpolation interval and making use of lower interpolation order can achieve optimal interpolation accuracy, in addition, both interpolation accuracy and stability are improved compared to the algorithm of nonsliding interpolation.