Blending polymers with different molecular structures or different properties has become a useful route in developing new, high-performance polymeric materials nowadays. It has clearly been understood that morphology mainly controls most of the properties of immiscible polymer blends. The blends of co-continuous morphology are of particularly important in cases that one phase is barrier or conductive. In this Study, Correlation between the rheology and morphology of PA/COC (Polyamide/Cyclic Olefin Copolymer) blends were studied in detail. Morphology development from matrix-dispersed to co-continuous and again to dispersed-matrix was well predicted using various linear viscoelastic analyses and confirmed via direct SEM experiments and continuity index analysis. It was shown that the difference between viscosity as well as elasticity of polymer components plays a dominant role in developing morphology micro-structure and phase inversion region. It was also shown that the phase inversion occurs at 40 wt.% of PA in the blends.