Abstract: PET was degraded by using ionic liquid as a catalyst in a glycol solvent, and effects of reaction temperature, reaction time, catalyst dosage, and ethanediol/PET ratio on degradation reaction were investigated. The results indicated that the ionic liquid based on 1-butyl-3-methyl imidazole hydroxide (［Pmim］OH) could well catalyze the degradation reaction of PBS, and an optimum alcoholysis condition could be achieved for the degradation reaction at a reaction temperature of 195 ℃, a catalyst dosage of 2.5 wt %, an ethanediol/PET ratio of 4∶1 and reaction time of 3.5 h. Structures of the degradation products were also characterized by Fourier-transform infrared spectroscopy and mass spectroscopy, which was identified as 2-hydroxyethyl methyl terephthalate.