The relationship between the morphology and rheological properties of PP/PA6/EPDM-g-MA ternary blends, at relatively low rubber phase contents, was studied in detail. The results showed that the size of composite droplets of core-shell microstructures decreased and increased after passing through a minimum due to competitive effects of the emulsification role of EPDM-g-MA and viscosity ratio. This trend in morphology development was well reflected in the relaxation spectrums of the blends. The morphology of discrete core-shell particles altered to the large clusters of core-shell particles at higher rubbery phase contents which led to alteration of viscoelastic behavior from liquid-like to solid-like. The morphology of high EPDM-g-MA content ternary blends was unstable particularly at higher temperatures which was evaluated using time-sweep rheological experiments and confirmed via direct SEM analysis.