Micro-thermal analysis (TA) is an exciting new innovation in the field of materials characterization. It combines the visualization power of atomic force microscopy (AFM) with the characterization capabilities of TA. Micro-TA can be used to characterize materials and surfaces, and to visualize the spatial distribution of phases, components. and contaminants in samples such as polymer blends. When two or more polymers are combined (incompatible blend), the microstructure and morphology have a direct impact on the materials final mechanical and chemical properties. Knowledge of the size and distribution of these phases can lead to a better understanding, and ultimately optimization of mechanical properties. In this study, micro-TA is used to examine the uniformity of high-density polyethylene and polystyrene blend with composition 70/30 and 50/50 (by weight) using different blend methods, including physical blending, blending in an extruder, and blending on a Haake mixer. Since the compatibilizer are commonly used in the polymer industry, the effect of compatibilization of block copolymers on the uniformity of a 70/30 (by weight) blend of high-density polyethylene (HDPE) and polystyrene (PS) is also investigated by micro-TA technique and the results are compared with that from other techniques, including scanning electron microscopy (SEM) and Raman spectroscopy. The compatibilizers investigated are several block copolymers, including poly(styrene-b-ethylene), S-b-E; poly(styrene-b-ethylene/propene). S-b-EP; and poly(styrene-bethylene/butene-b-styrene). The results from micro-TA shows the similar trend that from SEM and Raman. The results shows that S-b-E block copolymer is the most effective compatibilizer among the compatibilizer tested, which decreases the domain size of the dispersed polystyrene phase while improving its dispersion in the polyethylene matrix.