This thesis proposes a new on-board stationkeeping system suitable for the geostationary satellites operation and presents the results of the computer simulations conducted to verify the proposed system. The proposed on-board stationkeeping system receives pseudo-range signal from the ground equipments located at two different positions with long baseline, determines the orbit error deviated from a reference orbit in real-time and generates orbit control commands. To lower the complexity of the on-board stationkeeping logic and to improve reliability, a simple orbit controller based on fly the wire method is designed which makes the orbit roughly follow predetermined reference range data. And again to reduce the fuel consumption, the orbit controller using modified fly the wire method is proposed and analyzed through computer simulations. The reference range data are assumed to be generated through ground based computer simulation and embedded or uploaded with time tag. This paper also proposes a useful reference orbit generation algorithm suitable for control of adjacent multiple geostationary satellites. Finally, the performance of the proposed approach in multiple satellites control environment is verified through the computer simulations.