Abstract: Based on the property that the great majority of celestial motions in solar system can be described by the model of two-body problem with perturbations, we use the composition of algorithm to construct out a improved explicit symplectic algorithm with higher accuracy. Numerical results have shown that the algorithm have advantages in the computations of celestial orbits compared with usual symplectic algorithms.

Key words: two-body problem with perturbations, composition of algorithm, symplectic algorithm, along track error