Abstract: The principle of sliding generalized extended approximation method is introduced. Based on this algorithm,the relationship among different combinations of the number of nodes in unit domains, the number of approximation functions,the number of nodes in extension domain and the interpolation accuracy of three different BeiDou satellites is respectively discussed. The actual example shows that the three parameters of the three kinds of BeiDou satellites to achieve the best interpolation accuracy are different;as long as the appropriate three parameters are selected,the interpolation accuracy of the three different BeiDou satellites can reach a very high accuracy.This method is completely applicable to BeiDou satellites precise ephemeris interpolation.