A graft terpolymer of acrylonitrile (AN) and N-vinylcarbazole (NVC) onto ethylene-propylene-diene terpolymer (EPDM) was synthesized in toluene using benzoyl peroxide. The effects of EPDM content, mole ratio of NVC to AN, reaction time, reaction temperature, and initiator concentration in the graft copolymerization were examined. The synthesized AN-EPDM-NVC graft terpolymers (AEVC) were identified by infrared (IR) and H-1-NMR (nuclear magnetic resonance) spectra. The thermal stability, tensile strength, and light resistance of AEVC were investigated by using a Fade-o-Meter, thermogravimetric analyzer, and tensile tester. It was found that the heat resistance of AEVC is considerably better than that of acrylonitrile-butadiene-styrene (ABS) copolymer.