Pyrolysis-gas chromatography-mass spectrometry(Py-GC/MS)has been applied for analyzing in dissolvable and micro organic material,especially for the complicated polymer.In this paper,Py-GC/MS was used to analyze an unknown resin,combined with infrared spectroscopy(IR).The unknown resin was styrene-methyl methacrylate alternating copolymer,and the solvent in the unknown material was 3-phenoxy-1-propanol.