An analytical method od determination of luni-solat perturbations of the satellite motion is described here. The motion of perturbing body is described by trigonometrical series with the necessary accuracy. The determination of perturbations is made by numerous analytical transformations of the series by means of computer. As a result of these transformations the original accuracy is lost because of the limitation of the number of terms in series. The loss of accuracy is subjected to analysis by means of numerical tests and intotal accuracy of original series is estimated for fixed required accuracy of the calcualtion of satellite coordinates.