This paper presents a mixed duplex transmission method based on satellite communication TDMA which means satellite-ground link transmit/receive signals by FDD and ground terminal send/receive signals by TDD. The method designs a frame structure of mixed duplex transmission and a timing strategy of transmit/receive signals of up-link and down-link by analyzing the geographical location and transmission time of the user terminals within the satellite coverage area. The method solves the interference between the transmitting and receiving signals of the user terminals caused by the nearby frequency interval between the up-link and down link in the satellite communication FDD. It effectively reduces the isolation requirement and the size of satellite antenna, which is of great significance to the improvement of satellite communication capability of army's small weapon platform.