Piezoelectric ceramics are good candidate materials for sensor and aetuator applications, because of its ability to convert mechanical energy to electrical energy and vice versa. The response speed of Electro-mechanical converting signal in piezoelectric transducers is up to a few hundreds kilohertz, Therefore. they are widely used in vibration and acoustic system. In these applications, the nonlinearity of the materials is a main factor to consider when one designs the control system. In this paper, the nonlinearity of electro-mechanival conpling of PbZrxTi(1-x) O3 was investigated. Experimental results showed that the piezoelectric properties of PZT are greatly affected by the sequence and the amplitude of the applied voltage.