Commercial carbon fiber is sized with Bisphenol A type epoxy, a thermosetting resin, to prevent fiber damage due to friction during weaving and manufacturing processes. When the thermoplastic resin is used as the base material, the interface between the carbon fiber and the thermoplastic resin is very weak because the bonding force with the thermosetting resin is not good, which greatly affects the mechanical properties of the composite material. Therefore, in order to improve the mechanical properties of the thermoplastic composite material, a process of removing the epoxy sizing layer on the surface of the carbon fiber in a furnace is required. In this process, the physical properties of the carbon fiber are changed according to the change of carbon fiber heat treatment conditions. In this paper, the study was carried out to evaluate the tensile strength required for automobile parts by extrusion and injection of thermoplastic resin based carbon fiber composites. Depending on the heat treatment temperature and time of the carbon fiber was a slightly tensile strength of the carbon composite material occurs, the tensile strength of the carbon composite material with a 6 hour heat-treated carbon fiber was measured at 550 ℃ the highest to 93 MPa. When the heat treatment holding time is more than 6 hours or the heat treatment temperature is more than 600 ℃, it may be the damage to the carbon fiber, which can cause a decrease in the tensile strength of the carbon fiber composite material.