A miniaturized low-frequency FBG acceleration sensor based on symmetric cantilever beam was proposed. Firstly, the sensitivity and natural frequency expressions of the sensor were derived according to the mechanical model of the sensor structure. Then, the structural parameters of the sensor were optimized, and the static stress and modal analysis of the sensor were carried out by ANSYS Workbench. Finally, the sensor was made according to the analysis results, and its amplitude-frequency response, sensitivity characteristics, transverse anti-interference ability and impact response were studied through experiments. The experimental results show that the natural frequency of the sensor is 72Hz, the sensitivity is 681.7pm/g, the lateral interference resistance is less than 4.9%, and the volume is only 6.48cm3, which can be used for real-time monitoring of low frequency weak vibration signals below 50Hz.