Abstract: With the increasing distance of human space exploration, the traditional information transmission mode of phase shift keying(PSK) modulation is faced with challenges such as the limited transmission power at the transmitter and the high demodulation threshold at the receiver. On the basis of the position modulation commonly used in long-distance optical communication, this paper proposes a PSK modulation method based on position information for deep space communication. Block diagrams of the transceiver realization are also presented. Both theoretical analysis and simulation results show that the proposed modulation method has the characteristics of low demodulation threshold compared with the traditional PSK modulation, which can bring about further transmission distance and better transmission quality for the deep space communication.