Abstract: BiFeO₃ powder was prepare by Sol-Gel, and BiFO₃ films of different thicknesses were deposited on glasses. The effects of different thicknesses on the microstructure, ferroelectricity, leakage current characteristics, refractive index and extinction coefficient of the films were studied.Resultsshowed that with the film becoming thicker, the ferroelectricity improved and the refractive index and extinction increased; when the potential was low (U^1/2< 2), Poole-Frenkel was prominent for the leakage current, while FN tunneling had the biggest effect on the leakage current when the potential was high (1/U < 0. 25);thickness results of film and surface layer from different deposition times calculated by fitting profile were consistent with the atomic force microscope data.