The face shear vibration mode is generated in the piezoelectric single crystal with the zxt-45°cut in the ［011］polarization direction. Due to its advantages of high piezoelectric coefficient, high mechanical quality factor, high compliance coefficient and low cross-talk effect, the face shear mode has become an ideal choice for small size, high sensitivity piezoelectric sensors, and has a good application prospect in the vector hydrophones. In this paper, the voltage sensitivity expression of the face shear mode piezoelectric accelerometer is derived by analyzing the vibration principle of the face shear mode. The finite element analysis software was used to establish the face shear accelerometer model, study the influence of structural parameters on the voltage sensitivity and resonance frequency of the face shear piezoelectric accelerometer, and optimize the structure size. The final simulation results show that the open circuit voltage sensitivity of the face shear accelerometer is 389.72 mV/g, the working frequency band is 20 Hz-3 kHz, and the lateral sensitivity is less than 3.45%. The research results show that compared with the traditional shear accelerometer, the designed face shear accelerometer has 11.6% higher voltage sensitivity while the weight of the mass block is reduced by 50%, which provides a new idea for reducing the average density of hydrophones and improving the performance of underwater acoustic detection.