Abstract: Using the molecular dynamics simulation, this paper established the model of methyl methacrylate (MMA)-butyl acrylate (BA) copolymer system, and predicted the effect of monomer ratio on the glass transition temperature (T_g) and mechanical properties of the MMA-BA copolymer. The results showed that the T_g of MMA-BA copolymer increased with the increasing molar ratio of MMA to BA, which is consistent with the variation trend of T_g calculated by the Fox equation. The Young's modulus, shear modulus and bulk modulus of the MMA-BA copolymer increased with the increasing molar ratio of MMA to BA, which is consistent with the variation trend of Young’s modulus, shear modulus and bulk modulus of the MMA-BA copolymer films tested experimentally.