The quartz fiber was hollowed and the hollow fiber/phenolic resin composites were prepared by compression molding. The results show that the cavity diameter of hollow fiber is 4~7 μm. With increase of the fiber hollowness from 0 to 0.5, the mechanical strength of the fiber increases. Under the same fiber volume content, when the fiber hollowness increases from 0 to 0.5, the density and thermal conductivity of the composites decrease from 1.63 g/cm³ and 0.49 W/(m·K) to 1.46 g/cm³ and 0.41 W/(m·K), respectively, and the ablation resistance remains unchanged. The hollow fiber/phenolic composites prepared by this method behave good thermal insulation performance and ablative properties.