A new method to prepare the graft copolymers that have an ethylene-propylene-diene terpolymer (EPDM) rubber backbone and poly(methyl methacrylate) (PMMA) branches was described. Firstly, the brominated EPDM (EPDM-Br) was produced by the reaction between the EPDM and N-bromosuccinimide(NBS), then the EPDM-g-PMMA was created by the ATRP of MMA initiated by EPDM-Br in the presence of CuBr/bpy at 90 degrees C. The study shows that the free radical transfer grafting polymerization does not existed in the ATRP of MMA initiated by allyl bromide/CuBr/bpy in the presence of pure EPDM. The propagation of the PMMA graft chains are in situ initiated by EPDM radicals which is created through the reaction between the EPDM-Br and CuBr. Moreover, the reaction conditions, such as solvent, reaction time, molar ratio of EPDM-Br : CuBr: bpy, were examined. The maximum graft efficiency(93%) was obtained at 90 degrees C for 20 h, when the ratio of EPDM-Br : CuBr : bpy was 1 : 0.8 : 2.4. The graft copolymers were characterized by solvent extraction. LR and H-1-NMR spectra technique.