Abstract: In order to meet the needs of the ultralong range and high speed space laser communication, a kind of communication system with the emitter utilizing a 4beam fiber laser phased array operating at 1.06 m was designed. The seed and one of the 4 beams were modulated, respectively, and the modulation rates of the pseudorandom sequence were 53 Mb/s, 120 Mb/s and 155 Mb/s. The results show that the quality of the receiving eye diagrams quality is better with the seed directly modulation at the same rates, and the receiving eye diagrams can be further improved through controlling the phases of the beam array. In the experiment, the multicarrier characteristics of the phased array modulated respectively at 2 beams were studied. The 5/5.08 MHz and 20/40 MHz sine waves were used as the modulation signals, respectively, and the frequency domain signal can be observed at the receiving terminal after beam combination and phase controlling. Therefore, the space communication system feasibility based on the fiber laser phased array can be verified in the experiment.