Abstract: The invention concerns a method for retrieving styrene monomer from discarded polystyrene scarp through pyrolytic reduction. The method provided by this invention involves the application of metal oxide catalyst and putting alloy additives on the bottom of a pyrolyzer. When the temperature of the pyrolyzer reaches 250.degree. C., the discarded polystyrene granules 3-5 mm in diameter are continuously fed at a constant rate. At the temperature of 350.degree. C. the gas is introduced. The temperature is kept in a range of 450.degree.-500.degree. C., till a batch polystyrene is completely pyrolyzed. During feeding the polystyrene a reduced pressure distillation is carried out. The yield of a liquid distillate is 90% of the feed stock in weight. The recovery rate of styrene amounts to 70-75%. The present invention provides an effective method for solving environmental pollution caused by discarded polystyrene and for retrieving polystyrene.