The performance of HUSY zeolites in the degradation of polystyrene(PS) has been investigated. Degradation was carried out in a semi-batch reactor with a mixture of PS and catalysts at 400-450degreesC. The HUSY showed good catalytic activity for the degradation of PS with very high selectivity to aromatic liquids. The effects of catalyst acidity, reaction temperature and process time on the distribution of aromatics are discussed. The increase of process time and surface acidity enhanced the production of ethylbenzene. High degradation temperature favored the production of styrene monomer.