Polystyrene plastic is a extensively used synthetic materials, however there may be nonetheless no environment friendly, financial or environmentally pleasant recycling technique for waste polystyrene plastic, which has brought on critical environmental air pollution and a waste of assets. Herein, the tactic of nitric acid oxidative improve is used to transform polystyrene plastic right into a high-value chemical uncooked materials, benzoic acid. The yield can attain practically 90% at 180 °C inside 3 h, and the purity of the product is greater than 95%. On this course of, nitric acid is decomposed by warmth to generate nitrogen dioxide and oxygen, which react with the carbon-centered radicals shaped at weak websites on the lengthy chain of polystyrene and additional generate peroxy radicals and hydroxyl radicals. The formation of oxygen-containing purposeful teams promoted the fracture of the C–C bond and finally shaped benzoic acid. As well as, this technique additionally has good remedy results on real-life polystyrene plastic merchandise. This analysis offers a brand new technique for the recycling and high-value utilization of waste polystyrene plastics. The intrinsic materials worth of polymers will be maintained by recycling purposeful chemical substances by oxidative improve.