Transparent organic-inorganic hybrid hard coating films were prepared by the addition of SiO2 or ZrO2, as an inorganic filler to improve the hardness property, filler was highly dispersed in the acrylic resin. To improve the compatibility in the acrylic resin, SiO2 or ZrO2 is surface-modified using various silanes with variation of the modification time and silane content. Depending on the content and kind of the modified inorganic oxide, transparent modified inorganic sols were formulated in acryl resin. Then, the sols were bar coated and cured on PET films to investigate the optical and mechanical properties. The optimized film, which has a modified ZrO2 content of 4 wt% markedly improved in terms of the hardness, haze, and transparency as compared to neat acrylate resin and acrylate resin containing modified SiO2 content of 8 wt%. Meanwhile, the low transparency and high haze of these films slowly appeared at SiO2 content above 10 wt% and ZrO2 content of 5 wt%, but the hardness values were maintained at 2H and 3H, respectively, in comparison with the HB of neat acrylate resin.