Abstract: Three-dimensional braided carbon fiber reinforced silicon carbide(3D-B C_f/SiC) composites were fabricated via polycarbosilane (PCS) precursor infiltration and pyrolysis processing assisted by hot-pressing. The influences of hot-pressing processing on the densities and mechanical properties of 3D-B C_f/SiC composites were studied. The results showed that the densities and mechanical properties of the composites were enhanced greatly by using hot-pressing processing after the first precursor infiltration during the fabricating of Ceramic Matrix Composites. The density,flexural strength,fracture toughness and shear strength of the composites, which were hot-pressed at 1600℃ for 1hour with a pressure of 10MPa in the first pyrolysis cycle and treated subsequently with six times of PCS precursor infiltration and pyrolysis under atmospheric pressure, were 1.79 g/cm³,672MPa,18.9MPa·m^1/2 and about 50MPa, respectively. The composites had good heat shock resistance and high temperature oxidation resistance.