The toughness of blends composed of nylon 6 and acrylonitrile-butadiene-styrene (ABS) compatibilized by using styrene-maleic anhydride (SMA) as a compatibilizer was measured over a wide temperature region. Results reveal that the combining effects of particle size and volume fraction of ABS on the toughness of nylon 6/ABS/SMA blends can be described through plotting brittle-ductile transition of the impact strength versus the interparticle distance (ID) on the assumption that ABS domains relieve the triaxial tension via internal cavitation or interfacial debonding. Moreover, the effect of interfacial adhesion on fracture behavior of nylon 6/ABS/SMA blends strongly depends upon the testing temperature. The difference of relation amomg temperature, fracture behavior and interfacial adhesion can be understood in terms of the deformation mechanisms, i.e. in the case of poor interfacial adhesion, the toughness lies on whether debonding existing at the interface relieves triaxial tension or not. It is believed that for good interfacial adhesion, internal cavitation followed by matrix shear yielding is a predominant factor for toughening. Furthermore, the fracture surface of these blends was probed to elucidate how interfacial adhesion affected the impact strength of the blends.