Abstract: Carbon fiber/phenolic aerogel composites (C/PA) were prepared through sol-gel polymerization of a phenolic resin followed by ambient pressure drying using carbon fiber mats as the reinforcements. The composites have low densities (0.27-0.40 g/cm³) and low room-temperature thermal conductivities (0.056-0.068 W·(m·K)^-1). The bend strength of the composite prepared from the pierced carbon fiber mat (P-C/PA) is twice that of the laminated carbon fiber mat (L-C/PA). The highest bend strength obtained was 35.9 MPa for the P-C/PA with a density of 0.40 g/cm³. Under ablation at 2000℃ for 60 s, the mass and linear ablation rates of the P-C/PA were 0.0043 g/s and 0.0147 mm/s, respectively. The phenolic nanoparticles in the aerogel were easily decomposed, evaporated and sublimed to remove superficial heat while the porous network of the aerogels effectively prevented heat transfer from the surface to the interior of the composite. C/PA composites are excellent candidates for bifunctional ablation/insulation applications.