In this paper, the effect of the orientational stretching rate on the piezoelectric properties and structure of the vinylidene fluoride-tetrafluoroethylene P(VDF-TFE) copolymer was studied. A relationship in the formation of the electret and piezoelectric states in P(VDF-TFE) has been established. The parameters of electrically active defects involved in the polarization process and determining the stability of the electret and, as a consequence, the piezoelectric states in P(VDF-TFE) are calculated. Keywords: electret state, polyvinylidene fluoride, tetrafluoroethylene, piezoelectric effect, thermal activation spectroscopy.