Sol-gel derived Pb (Mg1/3Nb2/3) 0.7Ti0.3O3 (PMNT) thin films were prepared by sping coating using a PbO cover coat technique, and investigated by X-ray diffraction (XRD), auger electron spectroscopy (AES), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The phase development of the PMNT film was significantly affected by the final annealing time. A perovskite PMNT film was obtained after annealing at 850℃ for 1 min. The electrical properties of the perovskite PMNT films were analyzed, by measuring the temperature and frequency dependence of dielectric properties, as well as the polarization hysteresis loop. The relaxor-like behavior and relatively low dielectric constant of the PMNT film is thought to be related to needle-like ferroelectric domains, which were formed due to self-coarsening of the polar microregion along the preferred orientation, as a result of extensive defects in the PMNT films.