Abstract: A brand-new methodl for increasing toughness and raising hydrothermal resistance ability of CFRP(carbon fiber reinforced plastic)was reported in this paper. This method is to treat and polymerize the graft modification surface of the carbon fiber and introduce a plastic and water-proof hybrid interphase into CFRP by cold plasma,so that the toughness of CFRP was increased by 148% and the fracture process of CFRP was transited from brittle fracture into tough fracture. The modulus,ILSs,T_g and relaxation activity energy of CFRP were not decreased but increased. The hydrothermal resistance ability of CFRP was improved very much and the retention ratio of ILSS was raised from 92.73% to 99.79% after 8 h in boiling water.