The sensing system and demodulation algorithm of laser array based on REC technology were analyzed and put forward. REC process met the low-cost mass production of laser array, and had the advantages of small size, and a greater practical value in the field of sensing in future. An efficient algorithm for laser scanning was proposed to measure the displacement of fiber Bragg grating (FBG) due to external stress. The system was unique in that accurate demodulation can be achieved by scanning only 0.4 nm bandwidth FBG spectrum instead of relying on scanning FBG main power peak and the algorithm can be applied in any FBG band, which enable using of wavelength-division multiplexing(WDM) for FBG sensing network. In the experiment, the single-channel and four-channel can accurately search the displacement of FBG reflection spectrum. Preliminary experiments demonstrate the effectiveness and feasibility of the proposed method, results show that the error of single-channel is less than 5 pm, four-channel′s is below 2 pm, stress and algorithm results show good linearity. It has certain reference value for the multi-channel laser array sensing.