Ferroelectric SrBi2Ta2O9(SBT) films were deposited on Pt/Ti/SiO2/Si substrates at 50$0^{circ}C$ using a sintered SBT target Bi and Ta targets by modified rf magnetron sputtering and then were annealed at 80$0^{circ}C$ for 10min in oxygen ambinet(760 torr) The composition of the SBT films could be easily controlled using the mul-ti-targets. The film composition of {{{{ {Sr }_{0.8 } {Bi }_{2.9 } {Ta}_{2.0 } {O }_{9 } }} was obtained with SBTd sputtering power of 100 W Bi of 25W and Ta of 10 W. A 250nm thick SBT films exhibited a dense and uniform microstructure and showed the remanent polarization(Pr) of 14.4 $mu$C/cm2 and the coercive field({{{{ {E }_{c } }})of 60 kV/cm at applied voltage of 5 V. The SBT films show practically no polarization fatigue up to {{{{ {10 }_{10 } }} cycles under 5V bipolar pulse. The retention characteristics of the SBT films looked very promising and the leakage current density of the SBT films was about 1.23$ imes${{{{ {10 }^{-7 } }}A/c{{{{ {m }^{2 } }} at 120kV/cm.