A special fiber made of carbon. It has the characteristics of high temperature resistance, friction resistance, electrical conductivity, thermal conductivity and corrosion resistance, and its shape is fibrous, soft and can be processed into various fabrics. Due to the preferred orientation of graphite microcrystalline structure along the fiber axis, it has high strength and modulus along the fiber axis. The density of carbon fiber is low, so its specific strength and specific modulus are high. The main purpose of carbon fiber is to composite with resin, metal, ceramic and carbon as reinforcing material to make advanced composite materials. The specific strength and specific modulus of carbon fiber reinforced epoxy resin composites are the highest among the existing engineering materials.