Transparent lead zirconium titanate (PZT) thin film is suitable for a variety of electro-optic application, and the increasing of the electrooptic coefficient of PZT film is one of the important factors for this application. In this study, the main processing variable for improving an electro-optic coefficient was the drying temperature: 300, 750, 350 and 500 degrees C in sol-gel derived PZT thin Trims. The highest linear electrooptic coefficient (1.65 x 10(-10) (m/V)) was observed in PZT film dried at 450 degrees C. The PZT film showed the highest perovskite content, polarization (P-max = 49.58 mu C/cm(2), P-r = 24.8 mu C/cm(2)) and dielectric constant (532). A new two-beam polarization (TBP) interferometer with a reflection configuration was used for electro-optic testing of PZT thin films which allows measurement of the linear electro-optic coefficient of thin film with strong Fabry-Perot (FP) effect usually present in PZT thin him.