This study is devoted to model vibrations of the piezoelectric cantilever beam via the finite element method (FEM), which are compared with the experimental results. To this end, the kinetic energy and the potential energy of the system are first derived from the basic physic laws of piezoelectric ceramics, the constitutive equations of the piezoelectric material, in terms of degrees of freedom of nodes. The governing equation of system is established by the uses of FEM technique and Lagrange’s equation for formulation. The case of a bimorph piezoelectric cantilever beam is considered to verify the validness of the modeling technique proposed. Numerical simulations and experimental study are next conducted and compared to ensure the effectiveness of the modeling method. In experiment, the displacement of the piezoelectric cantilever beam is measured by a laser displacement sensor, and then the sensor signal is feedbacked to a spectrum analyzer which is capable of showing the frequency response of the real system. The differences between the numerical simulations and those of experiments are small and non-critical, which confirm the efficacy of the proposed modeling technique.