AbstractA high sensitive micro-seismic fiber Bragg grating (FBG) sensor system based on narrow line width distributed feedback (DFB) laser is realized by using filtering demodulation. Sensitivity of micro-seismic FBG sensor lies on the structure of the sensor shell and the shape of the reflectivity spectrum of FBG. Experiments on the sensor system's frequency character have been done. Results show that this sensor has the smallest acceleration of 1mm/s2. The experiments on coal mine exhibit that the sensor can be used to measure micro-seismic sigmals. So the FBG sensor is feasible to have practical use to measure micro-seismic signals because the sensor has high sensitivity and is easy to be fabricated, it has good low frequency response and the interrogation system is simple, low cost.