In this study a Finite Element Analysis for cantilever plate structure excited by proof mass is presented. To investigate the influence of different geometry parameters like thickness, length and width on the maximum deflection and resonance frequency. Configuration of piezoelectric actuators attached to the plate structure in order to identify the optimal configuration of the actuators for selective excitation of the mode shapes of the cantilever plate structure. The Finite Element Modeling based on ANSYS12.0 package using modal analysis and harmonic analysis is used in this study for cantilever plate structure excited by patch type of piezoelectric plates of PZT-5H4E of different geometrical parameters like thickness, length & width on the cantilever beam. To study the maximum deflection , the readings are taken by varying different geometry parameters . With this different geometrical parameters first modal analysis is done to know the different modes shapes and their natural frequencies and the frequency of particular mode shape at which the deflection is maximum. Then in the second stapes Harmonic Analysis is carried out near same frequency and the deflection amplitude is found out. Thus simulation of a cantilever beam is done by varying different thickness of piezoelectric plates and the substrate material. The same simulation is carried for different lengths’ & width. Finally the results are combine presented on graph , which clearly shows the effect of variation of geometry parameters on the beam deflections and accordingly change in natural frequency.