ABSTRACTMullins effect and its reversibility of ethylene–propylene–diene terpolymer/carbon black vulcanizate and polypropylene/ethylene–propylene–diene terpolymer thermoplastic vulcanizate under compression mode were investigated systematically. Morphology studies showed that sphere-like ethylene–propylene–diene terpolymer particles were dispersed evenly in the etched thermoplastic vulcanizate surface with diameter of 5–7 µm. The results showed that thermoplastic vulcanizate demonstrated characteristic features (hysteresis of energy, residual deformation accumulation, stress softening) of Mullins effect. Compared with that of ethylene–propylene–diene terpolymer/carbon black vulcanizate, the polypropylene/ethylene–propylene–diene terpolymer thermoplastic vulcanizate had much higher stress and its stress softening phenomenon was more obvious. The reversibility of Mullins effect showed a temperature-dependent feature and was enhanced with increasing temperature.