Rheological measurement has been a preferred approach to the characterization of the structure and phase behaviors for multi-component multi-phase polymer systems, due to its sensitive response to the changes of structure for these heterogeneous polymers. In the present article, recent progresses in the studies on rheology for heterogeneous polymer systems including phase-separated polymeric blends and block copolymers are reviewed, mainly depending on the results by the authors’ research group. By means of rheological measurements, not only some new fingerprints responsible for the evolution of morphology and structure concerning these polymer systems arc obtained, also the corresponding results are significant for design and preparation of novel polymeric structural materials and functional materials. Rheological measurement has been a preferred approach to the characterization of the structure and phase behaviors for multi-component multi-phase polymer systems, due to its sensitive response to the changes of structure for these heterogeneous polymers. In the present article, recent progresses in the studies on rheology for heterogeneous polymer systems including phase-separated polymeric blends and block copolymers are reviewed, mainly depending on the results by the authors’ research group. By means of rheological measurements, not only some new fingerprints responsible for the evolution of morphology and structure concerning these polymer systems arc obtained, also the corresponding results are significant for design and preparation of novel polymeric structural materials and functional materials.