In this work, the relationship between properties and morphologies of PA6/EPDM-g-MA/HDPE ternary blends was studied. Two processing methods (one- and two-step methods) were applied to prepare the PA6/EPDM-g-MA/HDPE ternary blends. The dependence of the phase morphology on interfacial interaction and processing method was discussed here. It was found that core-shell morphology (core: HDPE, shell: EPDM-g-MA in PA6 matrix) appeared in PA6/EPDM-g-MA/HDPE ternary blends, and in comparison to the blend prepared by one-step method, the core-shell morphology with thicker EPDM-g-MA shell appeared in the blend prepared by two-step method. In this case, a super toughened PA6 ternary blends with the Izod impact strength of 72.51 kJ/m(2) which is 4-5 times higher than PA6/EPDM-g-MA binary blend and 9-10 times higher than pure PA6 could be achieved. Moreover, the rheological results indicated that the storage modulus of ternary blends was heavily dependent on the phase morphology. The core-shell structure with thicker EPDM-g-MA shell would weaken the contribution of interfacial energy to the storage modulus of ternary blends. (C) 2012 Elsevier Ltd. All rights reserved.