The microstructure, mechanical properties, the mechanisms of strengthening and toughening for the 10%C f/SiO 2 composite prepared by vacuum hot pressing, were studied. The SiO 2 glass matrix crystallized partially after hot pressing. The composite has a lamellar structure with the carbon fibers in parallel with the hot pressing plane. The bending strength, fracture toughness and fracture strain of the composite are significantly improved, compared with that of the matrix. Bridging and pulling out of carbon fibers and crabon fibers and crack deflection induced by the carbon fibers are the principal mechanisms of strengthening and toughening.