For the design of vibration control systems of composite structures using piezo-ceramic actuators, it is necessary to obtain an accurate system model. Especially, the information related to natural modes, damping ratios and modal actuation forces appears in the governing state space equations. A refined finite element analysis based on the layerwise displacement plate theory has been performed to obtain the system parameters of composite plates with piezoelectric actuators. In this study, the present finite element method has the capability to take account of the stepped effect due to partly bonded piezo-ceramics. Also modal testing techniques have bean applied to identify the system parameters experimentally. Through the comparison of numerical results with experimental data, the validity of the numerical procedures has been proved.