PLZT films have many significant applications in the field of integrat ed optics because of their desirable physical properties,such as dielectric properties,electric-optic eff ect and polarization insensitivity.A certain thickness of the electro-optic film is needed in the ap plication of integrated optical devices.Currently,it is hard to obtain more than 3μm PLZT thin film,because th e film is very easy to crack as the process is repeated for several times and the high-temperature annealing treatm ent is taken during the fabrication of PLZT thin film by sol-gel methods.In this paper,a 4.6μm thick PLZT thin fil m was fabricated on Nb-doped strontium titanate (NST) substrate using sol-gel methods by adding tr iton X-100as the stress crack inhibitor in order to reduce the propagation loss in the applications of i ntegrated optical devices effectively.The effect of the added amount of triton X-100on the film propert y is studied experimentally. And the film cracking can be eliminated effectively by optimizing the triton X -100amount.Meanwhile, the obtained film is characterized by optical microscope,scanning electron mic roscopy (SEM),X-ray diffraction (XRD),prism coupler and step profiler.The results show that the pe rovskite PLZT film is obtained after rapid thermal annealing at 650℃ for 30min,and the flatness of the film surface is less than 30nm with the average particle size of 50－100nm.The measured refractive indices of the PLZT (8/65/35) and the PLZT (11/65/35) films are 2.4029and 2.3885,respectively at the wavelength of 1550nm.They can both be used for PLZT e lectro-optical device fabrication.