Carbon nanotubes have unique tubular structure and excellent mechanical, electrical, optical and thermal properties. They are widely used in aviation, aerospace, electronics, communication, chemical industry, biology, medicine and other fields. However, because carbon nanotubes are easy to agglomerate, almost insoluble in any organic solvent and have poor wettability with other substances, they can not be evenly dispersed in solution or composites, which seriously limits their application in various fields. Therefore, it is necessary to functionalize carbon nanotubes in order to expand their applications in composites.