Abstract: The ablative properties of carbon fiber/phenolic resin (CF/PR) composites were investigated for a graphene oxide (GO)- and a graphitic carbon nitride (g-C₃N₄)-modified matrix with contents of 0.05, 0.1 and 0.2 wt%, respectively. Both the CF/(g-C₃N₄-PR) and CF/(GO-PR) composites showed much better ablation resistance than the one without g-C₃N₄ and GO. The optimum contents of g-C₃N₄ and GO are both 0.1 wt% giving mass ablation rates for CF/(0.1% g-C₃N₄-PR) and CF/(0.1% GO-PR) that were respectively 44.42 and 28.96% lower than that of the CF/PR composite. The addition of g-C₃N₄ and GO increases the char yield and the degree of graphitization of the char near the fibers during ablation, which benefits heat dissipation and thereby increases the ablation resistance.