Ba 0.5Sr 0.5)TiO 3 ferroelectric thin films with pure perovskite structure and good dielectric and insulating properties were prepared by Sol-Gel processing. It was found that the purity and crystallinity and dielectric constant of (Ba 0.5Sr 0.5)TiO 3 ferroelectric thin films increased and the leakage current density decreased with the increase of temperature. Films treated at 750℃ for 1h showed good and stable properties with a dielectric constant of 250 and a dielectric loss of 0.030 and a leakage current density of 6.9×10 -8A/cm2. The high dielectric constant, low dielectric loss and leakage current density may originate from the good Purity and crystallinity of the films. The J-U characteristics of films indicated that the conduction of the films obeyed the mechanism of the space-charge-limited injection model.