The expandable phenolic resol resins were synthesized by phenol,cardanol and paraformaldehydein the presence of alkaline catalyst (20%NaOH solvent).The surfactant made by self,foaming agent and acid curing agent made by self were used to mix with the expandable phenolic resol resin to prepare phenolic foam plastic.By analyzing the cardanol content with single-factor,the effects of the content of the cardanol on the physical characteristics,micro-structure and thermal stability of the phenolic foam were studied.The results indicated that cardanol can improve the compressive strength and bending strength of phenolic foam plastic.In addition,the onset degradation temperature was increased and the thermal stability was improved.