The improved digital signal processor DSP circuit of synthetic impedance is adopted instead of traditional piezoelectric shunting damping circuit in vibration control.The principle and implementation of the DSP circuit of synthetic impedance are analyzed in detail.The shock Absorption and noise reduction by piezoelectric damping with the DSP circuit of synthetic impedance is tested in an acoustic tunnel

and the single mode result of vibration damping is given and compared with that of traditional piezoelectric shunting damping circuits.The experimental result shows that this passive control scheme can achieve much better performance in vibration control.The further study on the development of the multiple mode and adaptive passive vibration control with DSP circuit of synthetic impedance is proposed.