Abstract: The satellite orbit is described by 15 parameters considering the one scale perturbation in COMPASS, and the bit distribution of navigation message is also consistent with GPS. But because the constellation of GPS is consisted of MEO whose period is approximately 12 hours, the parameterized program and bit distribution program may not applicable to GEO and IGSO which have higher orbit. In the system design of COMPASS, the ephemeris parameters accuracy losing have been taken into consideration, which is caused by the little inclination and small eccentricity of GEO. In the operation of system, thought the accuracy losing is eliminated, in special intervals, some parameters exceed the distributed bit limitation when the ephemeris parameters are coded into navigation message. The phenomenon and regulation of parameter’s exceeding limitation in the operation of system are introduced, and then the reasons are illustrated according to the ill-conditioned equation and the orbital characteristics, Some fitting algorithms are designed on the condition of avoiding accuracy losing, and the experiments are carried out with the actual observation data. The results proves, it is efficient to eliminate the parameter exceeding for the method of fixing one parameter while computing the others or the method of parameter ridge estimate.