The working principle of the differential pressure fiber vector hydrophone and its elements are introduced,and the influence of the equivalent treatment of the fiber layer on the simulation results is analyzed in this paper.Based on the finite element method, the performance of differential pressure fiber vector hydrophone is simulated.Based on the parameters selected by the simulation model, a differential pressure fiber-optic vector hydrophone sample is developed and tested at a frequency of 20 Hz to 1 000 Hz.The test results show that the simulation results of the phase sensitivity of the acoustic pressure are basically consistent with the experimental results, and the average difference is about 1.0 dB.The results show that it is feasible to use the finite element method to simulate the acoustic pressure phase sensitivity of the differential pressure fiber-optic vector hydrophone.