Abstract: This paper deals with high-tensile-stength C/AI composites with σ_b> 760MPa fabricated by casting.PAN I carbon fibers coated with coatings are arranged in investment casting moulds in tows,and the moulds are infiltrated with molten AI-Si-Mg alloy under the condition of vacuum 4000 Pa and air prcssure of 0.75 MPa.The tensile strength of specimens containing fibers of 0.35 volume fraction reaches up to 764 MPa.The effects of fiber arrangement in tows on infiltration of molten metal and on toughness of composites are also discusseda.