The subsystem of flyaway satellite communication earth station antenna feed mainly completes the task of which is to receive and transmit communication signal effectively, and provide differential signal for the terminal receiver. The system is comprised of split mounting focal antenna with 0.9m caliber, corrugated horn, polarization, pitch rotary joint, duplexer and two port transceiver public networks. The feed works between two operation frequencies. The feed transmits signal with 14.000-14.5000GHz and receives with 12.200-12.750 GHz. Different from general satellite fixed station, antenna must point satellite quickly and accurately in order to adapt to the change of antenna attitude which is caused by complex geography environment. The antenna transmits and receives in the mode of polarization. And polarization plane can adjust manually between the range of positive and negative 90. The uplink branch is，the transmission signal come out from high-power amplifier, then get through duplexer and polarization adjustment device and finally enter into the antenna via feed horn. The downlink branch is，the signal which the antenna receives passes polarization adjustment device, and then gets through the wave of deliver resistance filtering device and the amplifier of field-effect tube and ultimately sent to the communication terminal.