The surface modification of SWCNTs by a radiation grafting for an enhancement of their dispersibility was described. The raw SWCNTs were dispersed in different concentrations of styrene or acrylic acid solution and then irradiated by γ-radiation at various absorbed doses. The grafting degree was dependant on the monomer concentration and the absorbed close. The successful preparation of polystyrene- or poly(acrylic acid)-grafted SWCNTs were confirmed by 1H NMR and TEM observation. The grafted SWCNTs exhibited a much better dispersibility than the pristine SWCNTs.