Abstract We disclosed an easy and efficient method for fabrication of carbon nanotube (CNT)/carbon fiber (CF) hybrid fiber in industrial scale. It was achieved by sizing CF tow with a sizing agent containing CNTs. To get better dispersion in the sizing agent, CNT was functioned by the chemical modification with an amine monomer. The hybrid fiber showed a uniform distribution of CNT on the surface of CF. Interfacial shear strength of CF reinforced epoxy composite was significantly improved by integrating CNTs at the interface. Such a facile method in preparing CNT/CF hybrid fiber provides great commercial potential for CF manufacturer.