Abstract: Pseudo-stochastic pulse can compensate for the deficiencies of a dynamic model in precise orbit determination. Because of the great number of pseudo-stochastic parameters, the efficiency of the conventional least squares estimation may be depressed. To resolve this problem, a method based on the theory of parameter pre-elimination and back substitution, is presented. This proposed method was validated by experiments, and the result shows that parameter estimation using this method is the same as that of the conventional least squares, but with improved efficiency.