Based on the theoretical model of the piezoelectric vibrator in piezoelectric bimorph cantilevers, the influence of piezoelectric vibrator structural parameters on the generating capacity of the piezoelectric generating device is analyzed. The electro-mechanical coupling model of the piezoelectric vibrator is established using ANSYS software to simulate the effects of structural parameters of the piezoelectric vibrator, such as block mass, cantilever length, and cantilever thickness, on the natural frequency and generating capacity. In order to verify the validity of the FEA model and compare it with the numerical results, the natural frequency and generating voltage of the piezoelectric cantilever with typical structural parameters are tested. The numerical results show that the structural natural frequency decreases as block mass and cantilever length are increased, and cantilever thickness is reduced. When the natural frequency of the piezoelectric vibrator with the matching parameters is close to the outside exciting frequency, the performance of the piezoelectric generating device can achieve optimal value.