In this work, highly functionalized carbon nanotubes (CNTs) were achieved using plasma inducing-graft technique, in which maleic anhydride (MAH) was used as graft monomer. Then they were introduced into epoxy resin (EP) curing system to obtain CNTs/EP composites. The modification performance of this proposed method was summarized and contrasted with that of argon (Ar) plasma atmosphere. Results show that these two plasma methods can improve CNTs’ surface activity, and corresponding optimum powers are both 60 W. Meanwhile, thin polymaleic anhydride film can be coated on the surface of CNTs during MAH plasma inducing-graft, which can make sure of effectively dispersion and adhesion of CNTs in epoxy. Such treatment can not only obtain highly functionalized CNTs, but also overcome its serious self-entangling and aggregation problem. Compared with those composites modified by argon (Ar) plasma, the mechanical and thermal properties of CNTs/EP composites modified by MAH plasma are greatly enhanced.