The effect of types of solvent on the dynamic properties of atactic poly(methyl methacrylate)s (a-PMMA)s chains in solution was studied by a molecular dynamics simulation technique with the condensed-phase optimized molecular potentials for atomistic simulation studies (COMPASS) force field. Five kinds of casting solvent molecules were randomly embedded into the a-PND4A matrix to construct various types of simulated a-PMMA solutions based upon experimentally obtained densities. The dynamic properties of polymer chains such as mean-square end-to-end distance , mean-square radius of gyration , and asphericity ratio / of polymer chains were analyzed. Simulated results revealed that the of the a-PMMA chains increased with the increase of the dipole moment of the surrounded solvent molecules. The asphericity ratio of polymer chains showed a high correlation to the molecular weight of solvents. Furthermore, the simulated radial distribution function of H-H atomic pairs in the system of a-PMMA solutions indicated that the expansion of a polymer chain depends mainly on the conformation of solvent molecules instead of the interaction between the polymer chain and the functional group on solvent molecules.