Hard Coating are needed to enhance both mechanical durability of the relative soft plastic and optical performance of the transparent plastic. Silsesquioxane and silica hybrid polymers(silica hybrid I and silica hybrid II) were used to improve polycarbonate(PC) and polymethylmethacrylate(PMMA) surface properties such as anti-scratch. flexibility, and optical performance etc. Flow coating was applied with curing temperature varied from 80 to 120℃ for different times. Light transmittance, adhesion, pencil hardness, abrasion resistance, hot water resistance and dry heat resistance of coating layer were investigated. The optimum properties was obtained when the ratio of silica hybrid II to silica hybrid I was 3.