The pyrolytic process and volatiles of PICA porous phenolics at different stages were investigated by TG-FTIR and PyGC-MS.The results demonstrated that PICA porous phenolics presented two evident weight loss processes.The desorption of small molecules of PICA porous phenolics took place during the first process and H₂O,CO₂,HOCH₂CH₂OH are the main volatiles.The molecular chain of porous phenolics broke up and phenols,benzene series,fused ring aromatics evolved during the second process and it is the main stage of thermal degradation. After high-temperature pyrolysis loose and porous char with a certain strength is formed by the combination of porous phenolics matrix with high porosity carbon fiber reinforcement.