Abstract: Ar, N₂ and O₂ were used as low-temperature plasma excitation gases to treat the surface of carbon fiber reinforced plastics (CFRP). The effects of plasma gas, discharge power and treatment time on the physicochemical properties, including wettability, roughness, microscopic morphology and chemical components of CFRP surface, were characterized by contact angle measurement, AFM, SEM and XPS. The adhesive joint property was investigated through tensile shear experiment and failure morphology analysis. Compared with untreated, the tensile shear strength of CFRP adhesive joints after Ar, N₂ and O₂ plasma treatment can significantly improve the bonding performance of CFRP, and when the plasma discharge power is 800 W and treatment time is 20 s, the adhesive joint strength increases by 138%, 172% and 253%, respectively. The surface test analysis shows that the improvement of CFRP adhesive strength after argon plasma treatment is mainly induced by improving the surface cleanliness and increasing the surface area for interfacial adhesive, and the failure modes of samples changes from interfacial failure to mixed failure mode with cohesive failure as the main mode. Compared with Ar, a greater number of polar chemical groups (—NH₂) are generated on the CFRP surface after N₂ plasma treatment, which increase the surface activity and further improve the interfacial adhesive strength between CFRP and adhesive. Compared with the above two gases, O₂ plasma etch the CFRP surface more vigorously, as well as reorganize the surface chemical groups, forming a more polar —COOH functional group, so that the specimen adhesive strength is improved most effectively, and the specimen failure mode changes from interface failure to substrate failure. In addition, under the excessively high density and energy of the active particles, the adhesive performance will be reduced to some extent with the expansion of the pores by plasma etching.