In the multi-beam satellite communication, accurate on-board antenna pointing control is required, because of narrow beam width. On the other hand pointing errors resident in on-board antennas have the tendency to increase due to manufacturing difficulty caused by enlargement of antenna reflector's size and also the deployment system. These reasons have made it necessary for attitude and antenna drive control systems to be incorporated in an antenna pointing control system. This paper describes system configurations and interface design of an on-board antenna pointing control system for 20/30GHz antenna in 1-ton class geostationary satellites. This control system was designed to satisfy a pointing accuracy requirement of 0.04° (3σ). Also described are the testing methods employed in and the results obtained from ground closed-loop tests of the control system.