Super-tough nylon 6 was prepared by using polyethylene-octene elastomer (POE) grafted with maleic anhydride as a toughener. The influences of maleating and a compatibilizer on interfacial adhesion and mechanical properties of nylon 6/POE blends were investigated in terms of mechanical testing, Molau tests, SEM observations, IR analyses, and rheological behavior. The results show that the unmodified POE has hardly any contribution to toughness of nylon 6, whereas the maleic anhydride-grafted POE (POE-g-MA) significantly improves the compatibility of POE with nylon 6 and sharply reduces its size in the nylon 6 matrix due to the in situ formation of a graft copolymer between POE-g-MA and nylon 6 during melt processing. With the POE-g-MA, a transition from brittle to ductile occurs. Besides, the use of a compatibilizer in nylon G/POE-g-MA system shifts the brittle-ductile transition curve to a lower POE-g-MA content, which is attributed, in part, to the chain-extending effect of CE-96 on the nylon 6 matrix leading to further reduction of the sizes of POE-g-MA in the matrix, in part, to the coupling reaction of CE-96 between POE-g-MA and nylon 6.