Self-mixing interference(SMI) is a new emerging measurement technology.It refers to the phenomenon in which the emitted power of a semicondctor laser varies when a small fraction of the light is backscattered or reflectged by an exgternal target and re-enters the laser active cavity.Then the single beam self-mixing interference is formed.The self-mixing signal(SMS) carries the movement information of the external target and thus vibration and displacement can be retrieve from a SMS.In this paper,a measurement system based on SMI is designed for measuring the dynamic performance of PZT.The PZT specimens with clinder and stack types have been tested.The measurement results show the dynamic response and hysteresis of PZTs can be measured with a high accuracy by this SMI approach.