In order to find out the dynamic peculiarity of piezoelectric-stack displacement-amplifying actuator, three methods: harmonic response analysis, impedance test and dynamic grating projection are used to analyze it. Experimental results indicate that the displacement-amplifying mechanism can provide large output torque; its response time is less than 0.3ms; its mutation time of displacement is less than 0.5ms, the fluctuation of displacement is less than 5um, and the change of displacement vs. voltage is linearity variety; its dynamic displacement is smooth, when discharging. After analyzing the actuator, some virtues of dynamic response peculiarity are shown: rapidly responding, tiny displacement fluctuates, fine displacement linearity, higher precision, large output torque, etc. Therefore it can be abroad applied in many micro-displacement control and drive systems, which need high precision and large displacement. Its application prospect is worth to expect.