In this paper a new type of polymerization of benzonitrile with boron trifluoride-anisole complex catalyst system is reported．It was found that when benzonitrile was heated with boron trifluoride-anisole complex at 350°for 7 hours

trimerization and polymerization of benzonitrile took place simultanously，producing the cyclic trimer and the polymer of benzonitrile respectively．The influence of the amount of boron tri-fluoride-anisole complex used relative tO benzonitrile upon the trend of trimerization and polymerization has been studied．The infrared spectrum of the polymer of benzonitrile shows no absorption band chracteristic of the —C三N group，but absorption bands at 6.0--6.1 μand 6.3—6.4 μ，which are indicative of acyclic conjugated—C=N—linkage．This shows that the poly-met may contain the following chain structure which is a new type of conjugated polymer．