Abstract: Transparent high refractive index epoxy-ZrO₂ nanocomposites were prepared by in-situ solvothermal method. FT-IR spectra, X-ray diffraction characterization and electron microscope images displayed that nanoscale zirconia particles were successfully synthesized and homogeneously dispersed into the epoxy matrix.Besides,the optical properties of the nanocomposites were researched. Results showed that the nanocomposites had excellent transparence and the refractive index of the nanocomposites was significantly enhanced and could be up to 1.73 at 633 nm in comparison with 1.51 of pure epoxy.