Abstract: Based on the experience of hot sizing process for metals, the high-temperature stress relaxation phenomenon of composites was utilized to rectify the profile of composite structures using the hot sizing process. L-shaped and C-shaped beams made of carbon fiber fabric/epoxy were manufactured. The hot sizing experiments were carried out using the homemade hot sizing tools to investigate the effect of hot sizing load and hot sizing period on the shape of the part. The feasibility of the hot sizing process for carbon fiber fabric/epoxy composite structures was also analyzed. It is found that the stress relaxation under high temperature is the major factor to induce deformation of the composite structure in the hot sizing process, and other factors can be neglected. Both hot sizing load and hot sizing period have great influences on the result of the hot sizing process. As for a certain composite structure, an appropriate hot sizing process can effectively control the shape of the structure and make the assembly of the part more convenient.