Abstract: For applying nano-particles to the functional finishing of textiles, Nano-ZrO2 sol was prepared by sol-gel method, and the PET fabrics was treated with the ZrO2 sol by dip-padding process. A thin layer of nano-ZrO2 particles was formed onto the surface of the fabrics after been cured. The effects of concentration of reactant, kind of hydrolysis promoter and the ratio of reactant and hydrolysis promoter to the particle size of ZrO2 sol were analyzed, and the optimal reaction conditions for preparing nano-ZrO2 sol were determined as follows: concentration of the reactant 0.10mol/L, oxydol as hydrolysis promoter, quality ratio of oxydol to ZrCl4 1:1. ZrO2 sol with about 60nm in diameter was obtained in optimal reaction conditions. The ultraviolet protection factor (UPF) of the treated PET fabrics reaches 185 from 86(cured at 150℃), which has a much lower ultraviolet ray transmission in UVA. The standard test to washing (soaping) showed that the UPF value still remains 132 after 50 washing cycles. The experimental results showed that the treated PET fabrics possess durable UV-resistance property.