An NVT ensemble molecular dynamics (MD) simulation, using a leap-frog algorithm, has been applied to calculate the diffusion coefficients of aromatic compounds in supercritical carbon dioxide under the infinite dilution condition. The Lennard-Jones (12-6) potential function was used as an intermolecular potential. The calculated results show good agreement with the experimental data, by using the intermolecular interaction parameters between unlike molecules, which are determined by Monte Carlo (MC) simulation to give good representation for the solubility data of aromatic compounds in supercritical carbon dioxide.