Uniform and transparent PbZr 0.40 Ti 0.60 O 3 (PZT) amorphous thin films were deposited on the fused silica substrates using a modified sol gel processing. The optical properties of PZT amorphous thin films were investigated in the wavelength range of 200～1100nm. The refractive index, the extinction coefficient and the film thickness were calculated by a classical envelope method. The dispersion of the refractive index is well explained by the single term Sellmeier relation. The band gap of the PbZr 0.40 Ti 0.60 O 3 thin films is about 3.78eV using Tauc's theory.