Abstract: Catalytic isothermal chemical vapor infiltration fabrication of carbon/carbon(C/C) composites was investigated by polarized light microscopy, SEM and XRD in order to speed up the deposition efficiency and to enhance the oxidation-resistance of the matrix carbon. The influence of Ni/ZSM-5 supported catalysts on the deposition rate of matrix carbon is investigated by comparing pure C/C composites and C/C composites added with catalytic Ni/ZSM-5 powder. Results show that the pyrocarbon growth rate is faster in carbon fiber cloth substrates doped with supported catalysts than in the undoped one. Both the microstructure of the pyrolytic carbon and its oxidation-resistance have a close correlation with the amount of Ni/ZSM-5.