The brittle-ductile transition is a very important phenomenon for polymer toughening. Polypropylene (PP) is often toughened by using rubbers, e.g., ethylene-propylene diene monomer (EPDM) has often been used as a modifier. In this article, the toughening of PP by using a new kind of rubber, known as elastomeric nano-particle (ENP), and the brittle-ductile transition of PP/EPDM/ENP was studied. Compared to PP/EPDM binary blends, the brittle-ductile transition of PP/EPDM/ENP ternary blends occurred at lower EPDM contents. SEM experiment was carried out to investigate the etched and impact-fractured surfaces. ENP alone had no effect on the impact strength of PP, however, with the same EPDM content, PP/EPDM/ENP ternary blends had smaller particle size, better dispersion and smaller interparticle distance in contrary to PP/EPDM binary blends, which promoted the brittle-ductile transition to occur earlier. The brittle-ductile transition is a very important phenomenon for polymer toughening. Polypropylene (PP) is often toughened by using rubbers, eg, ethylene-propylene diene monomer (EPDM) has often been used as a modifier. In this article, the toughening of PP by using a new kind of rubber, known as elastomeric nano-particle (ENP), and the brittle-ductile transition of PP / EPDM / ENP was studied. Compared to PP / EPDM binary blends, the brittle-ductile transition of PP / EPDM / ENP ternary blends occurred at lower EPDM contents. SEM experiments were carried out to investigate the etched and impact-fractured surfaces. ENP alone had no effect on the impact strength of PP, however, with the same EPDM content, PP / EPDM / ENP ternary blends had smaller particle size, better dispersion and smaller interparticle distance in contrary to PP / EPDM binary blends, which promoted the brittle-ductile transition to occur earlier.