The degradations of polystyrene(PS) and the mixture of PS/polypropylene (PP) in supercritical water were studied in this article. The influences of conditions on the degradation, such as reaction time, temperature and material ratio of water/plastics were investigated. The results show that PS and PS/PP can be degraded into oily product in supercritical water. The reaction temperature and time are the major elements effecting on the degradation. The degradation temperature of mixture shall base on the more ...