To deal with the difficulty in realizing optical phase-locked loop (OPLL) and shorten capture time in satellites coherent light communication, a heterodyne detection and digital signal processor (DSP) based integrated method of communication and velocity measurement is proposed, which uses the frequency shift estimation and phase recovery technology in optical fiber communication. Principle and feasibility of the method are analyzed theoretically and verified experimentally. Simulation results show that when the received power is higher than -48.14 dBm under the mode of communication, the bit error rate (BER) of the system is better than 10-4, and when the signal noise ratio (SNR) is higher than 17 dB under the mode of velocity measurement, the estimation accuracy of the satellite radial relative velocity is superior to 0.62 m/s.