In order to assemble the fiber acoustic sensor automatically and accurately, an experimental system composed of intensity collection, sensitivity analysis and distance location was proposed. At first, by collecting the received intensity data at different operating distances, the characteristic curve of sensor was obtained. Then, these intensity data were analyzed to get the sensitivity characteristics of sensor, such as the sensitivity and linear operating range. Meanwhile, the optimum operating distance where the sensor has the best performance was confirmed. A feedback control signal was sent back to adjust and locate the optimum operating distance. A sensor with parallel fibers was set up by the proposed system. Experimental result indicates that the sensitivity of sensor is 16 mV/Pa at the optimum operating distance of 160 μm.