Thermal study of high-energy electron-irradiation binary blends of ferroelectric P(VDF-TrFE) copolymers has been investigated by X-ray diffraction, differential scanning calorimetry (DSC) and thermally stimulated depolarization current (TSDC). X-ray diffraction shows some degree of mixing inside a crystal lattice due to significant changes in the ferroelectric-to-paraelectric phase transition behavior from all-trans to trans-gauche conformation in nanometer range after irradiation. In DSC thermograms, it is found that both the Curie temperature and melting temperature decrease with the dose and that the F-P transition temperatures and enthalpies of two individual copolymers and the blend merge into one with the increase of dose, indicating that there exists a strong lattice coupling between the two copolymers. The peaks observed in TSDC spectra of the blends exhibit the phase transitional characters of the parent copolymers which demonstrates that the miscibility in the crystalline region for their large compositional discrepancy. The distribution of temperature peaks in TSDC also show that the existence of two types of crystallite in the blend which become more clear after irradiation, confirming the X-ray and DSC results.