In this article, the morphology, crystallization, and rheological behaviors of polypropylene (PP)/ethylene-propylene-diene terpolymer (EPDM) binary blend and PP/EPDM/calcium carbonate nanoparticles (nano-CaCO3) ternary blend were investigated. Two processing methods, i.e., direct extrusion and two-step extrusion, were employed to prepare the PP/EPDM/CaCO3 blend. The influence of EPDM and nano-CaCO3 respectively on phase morphology and properties of PP/EPDM blend and PP/EPDM/CaCO3 blend were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and dynamic rheometer. The crystallinity and crystallization temperature of PP/EPDM blend were improved in comparison to pure PP due to addition of EPDM, but kept invariable with the increased EPDM loading. As the EPDM content was increased, the mobility of PP molecular chains was weakened. Compared with direct extruded blend, less and finer nano-CaCO3 was dispersed in matrix of two-step extruded blend. Accordingly, the increased nano-CaCO3 in matrix gave rise to a weaker increment in crystallinity and crystallization temperature of two-step extruded blend, and a later platform of tand curve. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 510-519, 2012