A novel phthalonitrile functional biphenyl type novolac resin (PBN) was synthesized by nucleophilic substitution reaction between 4 nitrophthalonitirle and bipheny type novolac resin using base as catalyst. The results of rheology show that the complex viscosity of PBN resin is below 400 mPa·s at 180 to 300益,indicating that the resin possesses excellent processing capability. DSC curve of PBN resin reveales that the thermal polymerization reaction oc curs between 280益and 450益with peak temperature of 377益and exothermic enthalpy of 187 J/ g. PBN resin exhib ites excellent thermal stability. The results of TGA shows that Td 5 and R900益are about 529益and 78%,respectively