In order to apply P(VDF-TeFE) piezoelectric polymer to micro-generator as a membrane, the polymer is deposited on a substrate by spin-coating method. Since a solvent affects the film properties and surface stability, we have carried out the thermal process at a temperature higher than melting point. In the annealing process of a P(VDF-TeFE) thin film, electrical properties of the film was improved by an application of an electric field. The established study was the investigation of variations in characteristics by an application of a certain electric field. We have attempted to measure about the critical intensity of an electric field and investigate what the influences of the application is caused using a XPS spectrum in this study. Moreover, in order to control the intrusion of impurities, we have used the vacuum chamber to carry out the annealing process in it.