The work aims to simulate and analyze the release process and release mechanism of thymol from different PVA molecular chain lengths, based on molecular dynamics simulation. With polyving akohol as the research matrix, antibacterial (thymol) was added to jointly establish PVA/thymol polymer model to carry out molecular dynamics simulation. Based on the simulation, the release process of thymol in the PVA polymer under the respective molecular chain lengths (40, 80 and 160) was studied with regard to mean square displacement, diffusion coefficient and free volume. The free volume fraction of thymol molecules in PVA decreased with the increase of the molecular chain length, and the diffusion coefficient of thymol molecules in PVA would also decrease accordingly. The longer the molecular chain, the greater the interaction forces between the molecules, and this limited the movement of the chain. Different molecular chain lengths have an important effect on the release of antimicrobial agents in packaging materials. In the short chain structure, it is easy for the thymol molecules in the PVA to release and to slowly move rather than jump under the same conditions.