Abstract: The satellite clock error data interpolation is an important link in process of high accuracy positioning data, which has directly impact on positioning accuracy. However, the common interpolation and fitting methods have different disadvantages. The generalized extension approximation method is tried to apply to the process of Quasi-Zenith Satellite System (QZSS) satellite clock error data in this paper. The principles of Lagrange interpolation, Chebyshev fitting and Generalized extension approximation method are firstly introduced, and the differences between sliding and non-sliding. Afterwards, QZSS clock error data is used to discuss the relationship between the parameters (groups) value of the above three methods and the interpolation results accuracy. Finally, when the three methods take their respectively optimal parameters (groups), the accuracy of QZSS satellite clock error is compared. The simulation results show, as long as reasonable parameter combination is selected, that the generalized extension interpolation is completely suitable to QZSS satellite clock error, and the interpolation accuracy of the generalized extension approximation method is significantly higher than other two methods.