Aiming at the stability of smart structure vibration control, a model reference adaptive control (MRAC) algorithm based on Lyapunov's second method is used to suppress vibration of a simple plate. The state equations of Piezoelectric plate first-order and second-order mode are put forward and two adjustable parameters are determined. MRAC combining feedforward and feedback control style needn't be proved stability of closed loop control system. Simulation results show that the method have good effect whether transient disturbances excitation or persistent disturbances excitation.