As the multi-DOF ship motion in the ocean, the ordinary satellite antenna can not be normal used on the ship. A ship-borne automatic tracking system is introduced in this paper. First, the MCU will calculate the satellite antenna pointing solution according to GPS and electronic compass, and then will drive the motors to specified angle according to the azimuth, pitch angle and polarization angle. Finally, the antenna system will track the satellite automatically according to three-axis gyro sensor signals. In order to overcome the sensor drift and get better satellite tracking precision, a conical scan algorithm is used in the tracking system.