The films of copolymers of vinylidene fluoride with trifluoroethylene (VDF/TrFE) with different crystallinity were prepared by four methods, i. e. , as-cast, quenching in liquid nitro-gen, slow-cooling and annealing at 140℃. The complex dielectric constants were measured using an improved dielectric relaxation spectrometer whose precision increased to 2‰ from the original 1%. The dielectric relaxation of noncrystalline regions was found in accordance with the dielectric frequency spectra of quenched sample that the crystallinity was 20% below room temperature. Thereby, the relationship between the glass transition temperature and the component of copolymers was got.