The kinds and the properties of composite materials and superhard cutting-tool materials are introduced in this paper. By using five kinds of superhard cutting tools, such as polycrystal cubic boron nitride (PCBN), polycrystal diamond (PCD), thin film and thick film of chemical vapor deposition (CVD) diamond and carbon nitride (CxNy), two kinds of composite materials (fiber reinforced and particle reinforced) have been turned. Many experiment data have been gotten. It is shown that the superhard cutting tool is the best for machining composite materials. Moreover, surface finish and cutting force in composite material machining are discussed.