The SBT(SrBi2Ta2O9) thin films with Bi2O3 buffer layer were deposited on Pt/Ti/SiO2/Si substrate by R.F. magnetron sputtering method in order to improve the ferroelectric characteristics. In SBT thin films, the deficiency of bismuth due to its volatility during the process results in an obvious non stoichiometry of the films and the presence of secondary phases. Bi2O3 buffer layer was found to be effective to achieve lower temperature crystallization and improve ferroelectric properties of SBT thin films. Ferroelectric properties and crystallinities of SBT thin films with various substrate temperature of Bi2O3 buffer layer were observed, using X-Ray Diffraction (XRD), Precision LC (Radient Technologies. Inc.) and GDS (glow discharge spectrometer).