Abstract: Three kinds of ablation-resistant silicon fiber reinforced phenolic resin composite materials were compared in their weight lost rates, mechanical properties, macroscopic and microscopic morphologies after high temperature oxidation. It is found that the weight loss rates of the mixed braided composites are obviously higher than that of the single braided composite after high temperature oxidation. With increasing oxidation temperature the elastic moduli of both the mixed and single braided composites decrease. The single braided composite has the best ablation-resistant property among the three kinds of ablation-resistant silicon fiber reinforced phenolic resin composite materials.