A multi-component polymer of methacrylic acid (MAA) and butyl acrylate (BA) grafted onto ethylene-propylene-diene (EPDM) terpolymer was synthesized in toluene using benzoyl peroxide (BPO) as initiator. The effect of EPDM/MAA-BA ratio and MAA/BA ratio on the grafting ratio of polymerization was investigated. The products were characterized by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), surface energy, inherent viscosity, and atomic force microscopy (AFM). The results showed that the MAA and BA monomers were successfully grafted onto EPDM. Furthermore, after being grafted, the polarity of the surface of the EPDM-g-MAA-BA increased with increasing grafting ratio, and the morphology of its surface became more smooth.