Ablation under oxyacetylene torch with heat flux of 4186.8 (10% kW/m2 for 20 s was performed to evaluate the ablation resistance of C/C–SiC composites fabricated by chemical vapor infiltration (CVI) combined with liquid silicon infiltration (LSI) process. The results indicated that C/C–SiC composites present a better ablation resistance than C/C composites without doped SiC. The doped SiC and the ablation products SiO2 derived from it play key roles in ablation process. Bulk quantities of SiO2 nanowires with diameter of 80 nm–150 nm and length of tens microns were observed on the surface of specimens after ablation. The growth mechanism of the SiO2 nanowires was interpreted with a developed vapor–liquid–solid (VLS) driven by the temperature gradient.