Due to the orbit characteristics of the GEO satellite in Compass constellation, the multipath error in pseudorange measure cannot only be eliminated by the receiver, but also be amplified in the elimination of the ionosphere delay by dual frequency pseudorange combination, resulting in the accuracy deterioration of ionosphere delay monitoring by the monitor stations. Based on the slow-change characteristics of the GEO satellite orbit, this paper proposes a method of using real-time multipath estimation, which is extracted from previous days’ pseudorange measurements, to correct the multipath error in real-time ionosphere delay computation. Experiment results demonstrate that this method can eliminate the fluctuations in GEO satellite dual frequency ionospheric delay measurements caused by multipath error and enhance the dual frequency ionospheric delay measurements accuracy of low azimuth GEO satellites by 55.7 %.