Abstract: The master oscillator, power amplifier arrangement was experimentally investigated. The master laser was divided into 2 paths by a fiber beam splitter, and the two amplified beams were combined by a fiber coupler. A sample of the combined beam was relayed to a PC based on phase detection system which comprised photodiodes, preamplifiers and an A/D card. Phase corrections were calculated using Labview and the feedback voltages were applied to the phase shifters directly from analogue output channels. Coherent combining of two fiber lasers array was realized. After the control loop was turned on, optical path difference of two fiber amplifiers was modulo 2π, the output intensity was kept at the status of stable high brightness.