The coupling relationship between the structure mechanical impedance and the piezoelectric impedance of PZT sensor is analyzed based on the piezoelectric impedance model of the piezoelectricstructure.We research the testing method on the piezoelectric mechanic impedance.The piezoelectric impedance testing method is studied and the basic principle is given according to the damage monitoring method on the electromechanical impedance spectrum research in the piezoelectricstructure model.In this text,we test in the aluminium sheet,verify the testing method of piezoelectric and electromechanical and how various distance damage affect the piezoelectric electromechanical impedance spectrum.Above all, we research the feasible of impedance analysis method for damage monitoring. As the research result shows that PZT impedance will change with the distance of damage changing while it is excited by the high frequency.