[en] The preparation and properties of high refractive index nanocomposite material were studied. The TiO_2 nanoparticles were synthesized by sol-gel method using acetic acid as a chelating ligand. The nanoparticles were dispersed directly into the polymer matrix to prepare transparent high refractive index nanocomposite thin films. The refractive index of films will be enhanced with the increase of titania contents. The particles were characterized by X-ray diffraction (XRD), Transmission Electron Microscope (TEM), and Fourier Transform Infrared Spectroscopy (FTIR), respectively. The results showed that all samples with different amounts of TiO_2 exhibit good optical transparency. Furthermore, the pattern of the TiO_2 NPs shows a pure anatase phases. From TEM image, the TiO_2 has little agglomeration. The FT-IR spectrum indicated that acetate ions and titanium ions show good chelation. (paper)