C/SiC-HfC composites were prepared by PIP process with carbon fiber as reinforcement and polycarbosilane and polyalkyl hafnium as precursors. It was found that the C/SiC-HfC composites had lower density， and much better mechanical properties at high temperatures compared with C/SiC composites，and matrix with HfC had a better protection to the carbon fiber in the static oxidation test under 1 650 ℃. The density of C/SiC-HfC composites is about 1.92 g/cm³，the bending strength at room temperature is 245 MPa，and the high temperature bending strength is 424 MPa at 1 800 ℃. The better mechanical properties of C/SiC-HfC composites at high temperatures are due to the fact that the addition of HfC can inhibit the growth of silicon carbide and reduce the probability of large cracks in the matrix. The addition of HfC on the surface made the SiC oxidized to SiO₂ in time under 1 650 ℃ in air， SiO₂ coating was formed on the surface of the fiber and the matrix，which prevented the further oxidation inside the material.