Aiming at the need of three-dimensional vibration signal measurement in vibration monitoring, a three-dimensional acceleration sensor of fiber grating based on flexible hinge is designed. The vibration model of the sensor is established, the structure and working principle of the sensor are expounded, and the theoretical formulas of the resonant frequency and sensitivity of the sensor are deduced. The mathematical model of the sensor unit is constructed, and the key dimension parameters of the sensor vibration pickup structure are optimized by MATLAB. The sensor samples were processed and fabricated, and their performance was tested by vibration experiments. The experimental results show that the resonant frequencies of the sensor in the X, Y and Z axis directions are 673Hz, 667Hz and 1376Hz, respectively, the operating frequency bands are 0~220Hz, 0~220Hz and 0~450Hz, and the sensitivity is 72.3pm/ g, 70.2 pm/g and 83.1 pm/g. The designed sensor has good lateral anti-interference degree and can meet the requirements of three-dimensional vibration signal measurement.