Plastic materials are directly or indirectly emitted into the environment arousing increasing environmental concerns. This work focused on investigating the binding and the degradation mechanism of biodegradable plastics polyvinyl alcohol by oxidized polyvinyl alcohol hydrolase (OPH) purified from Pseudomonas. Molecular dynamics (MD) and quantum mechanics/molecular mechanics calculations (QM/MM) were performed for the investigation. The formation of hydrogen bonds between Gly65, Ser66, Va167 with ligand exert extremely important promotion effect on the reaction. Besides, significant electrostatic influence of Glu198 also contributes to the catalysis. These results provide valuable guidance to future mutation studies and enzyme engineering for efficient degradation of plastics.