The gamma-ray pre-irradiation induced method was employed to study the effect of chloroepoxypropane modification on the surface of carbon fibre (CF) and the interfacial properties of CF/epoxy. Systematic experimental work was conducted to determine the fibre surface topography, fibre surface energy, fibre tensile strength and interfacial adhesion of CF/epoxy before and after gamma-ray pre-irradiation grafting. The roughness and surface energy were all found to increase significantly. The tensile strength of carbon fibres was improved marginally by gamma-ray pre-irradiation. The surface modification of carbon fibres led to an improvement (at most 18.2%) of the interlaminar shear strength of CF/epoxy composites. The mechanisms of pre-irradiation of CF are proposed.