A new approach to the preparation of colorless and high transparent methacrylic resins was described. N-Alkyl methacrylamide, the alkyl substituent of which was methyl, cyclohexyl, or isobornyl, was employed to copolymerize with methyl methacrylate, giving the copolymer with enhanced glass transition temperature around 10-15 degreesC higher than that of homo-poly(methyl methacrylate). The comonomers, N-cyclohexyl methacrylamide and N-isobornyl methacrylamide, were prepared by reaction of methacrylonitrile with cyclohexene and camphene, respectively. All the three kinds of copolymers showed the water absorption similar to that of homo-poly(methyl methacrylate) after the samples were immersed in water for 2-8 days. The copolymers also showed high weather resistance toward sunshine in atmosphere for 16 months.