To improve the ablation resistance of PIP-C/SiC composites, zirconium carbide (ZrC)-modified SiC coating was prepared by chemical vapor deposition combined with slurry painting, then the ablation capability of the coated composites was tested under an oxy-acetylene torch. Compared with the uncoated composites, linear and mass ablation rates of the coated composites decreased by 73.6% and 76.4%, respectively. The formation of zirconia from the oxidation of ZrC improved the ablation resistance of the composites because of anti-oxidation performance, which absorbed heat from the flame and reduced erosive attack to C/SiC composites. Zirconia also acted as an accelerator for carbon fiber oxidation as it reacted with carbon during ablation. The heterogeneous reactions controlled the ablation of the composites.