Abstract: Pyrolysis of polyphenylene sulfide has been investigated by pyrolysis-gas chromatography-mass spectroscopy at the different temperatures between 350 ℃ and 750 ℃. Its composition of pyrolysates has been analyzed. During pyrolysis of polyphenylene sulfide, polymeric chain scissions take place as a successive removal of the monomer units from the polymeric chain, and the major decomposition products consists of dimeric and trimeric chain fragment. The chain scissions are followed by secondary reactions, which lead to a variety of compounds. The cyclic and rearrangement reactions can also take place during pyrolysis.