Poly (vinylidene fluoridetrifluoroethylene) (P(VDFTrFE)) thin films were deposited on polyimide substrate using horizontal LangmuirBlodgett(LB) technology. Xray diffractions indicate that the films have good crystallinity with (110) preferential orientation for films with different thickness. The optical dispersion of the films were measured by variableangle spectroscopic ellipsometry. The data Ψ and Δ at multiple incident angels (θ=75° and 85°) were fitted using the Cauchy model. The refractive index, extinction coefficient，absorption coefficient and thickness of each film were obtained. The ferroelectric of the films were studied. The remnant polarization is up to 6.3μC/cm2. The coercive field is 100MV/cm. The dielectric measurement for the film shows two distinctive phase transitions, ferroelectricparaelectric phase transition and β relaxation.