Abstract: Carbon fiber reinforced polytriazole matrix (CF/PTA) composites, a novel low temperature cured and high temperature resistant series, were developed originally by East China University of Science and Technology. In order to improve the interfacial bonding strength of CF/PTA composites, based on molecular structures of the resin matrix, the carbon fiber reinforcement and the sizing agents on carbon fiber surfaces, three N-base coupling reagents containing different functional groups such as azido, isocyanate and aziridine were designed and employed to treat the fiber surfaces. The chemical bonding mechanisms were researched in terms of the analyses from X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and atomic force microscope (AFM). The characterizations suggested that the N-base coupling reagents reacted with the resin matrix polytriazole (PTA) and the carbon fiber reinforcement respectively, and effective chemical bridges were established between PTA and carbon fiber by N-base coupling reagents. Significant improvement of the interlaminar shear strength (ILSS) were achieved when only 2% mass fraction of N-base coupling reagents were added to the composites. The most available process is carbon fiber treatment with isocyanate-containing coupling (A1), which improved the ILSS by about 70%; while the application of azido- or aziridine-containing reagents were along with heating or concentrated nitric acid treatments, which increased the ILSS by 89% and 86%, respectively.