Abstract: The SrBi₂Ta₂O₉ thin films were prepared on quartz substrates by using the RF magnetron sputtering method.The thickness of the thin film is 349nm and the linear refractive index was 3.05.The third-order nonlinear optical properties of the films were measured by the Z-scan technique.The nonlinear refractive index n₂ and the nonlinear absorption index β at 532nm wavelength are 2.56×10^-8esu and 3.9×10^-4esu,respectively. The real part of the third-order nonlinear optical susceptibility χ^（3） is 8.29×10^-9esu and its imaginary part is 1.08×10^-9esu.