The research and development of high-performance polymer materials with excellent gas barrier properties has gained considerable attention from the viewpoint of expanding their applications in various fields, including tire automobile parts and the polymer film industry.Natural rubber (NR) has been widely used as a rubber material in real-life, but its application is limited owing to its poor gas barrier properties.In this paper, we study the gas barrier properties of NR, epoxidized natural rubber (ENR), and their blend compositions by using mol. simulation.The results show that ENR-50 has superior oxygen barrier properties than those of NR.Moreover, the oxygen barrier properties of a blend of NR/ENR-50 improve with increasing volume fraction of ENR-50.The trend of improved oxygen barrier properties of NR, ENR-50, and their blend is in good agreement with exptl. observations.