Abstract: The carboxyl epoxy resin/nano ZrO2 nanocomposites were prepared by free radical copolymerization with the nano ZrO2 nanoparticles modified by Triethoxyvinylsilane(A-151), vinyl methyl ether and methyl acrylic acid. The modified nano ZrO2 nanoparticles and the carboxyl epoxy resin/nano ZrO2 nanocomposites were characterized by fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The results show that the surface of the modified nano ZrO2 Nanoparticles was covered by the carbon-carbon double bonds. TEM results show that the nano ZrO2 nanoparticles were evenly dispersed in the polymer matrix and its surface generate layer by reaction of vinyl methyl ether and methyl acrylic acid. The carboxyl epoxy resin/nano ZrO2 nanocomposites were applied in leather tanning process. The application results show that the shrinkage temperature, thickening and softness of leather tanned by the carboxyl epoxy resin/nano ZrO2 nanocomposites with 3% chromium powder significantly improve compared with these of leather tanned by chrome and the content of Cr2O3 in tanning waste water effectively reduce.