The crystals of polyphenylsilsesquioxane (PPSQ) and isotactic polystyrene (i-PS) blends prepared from their toluene solutions had been studied by optical polarized microscope and DSC. Some big bright regular parallelogram-like single crystals from PPSQ with coarse surface are observed (PPSQ greater than or equal to 90%) and no regular crystals could be formed (PPSQ less than or equal to 70%), however, at PPSQ less than or equal to 10%, this blend formed irregular continuous crystals from i-PS similar with pure i-PS. Crystallinity of rich-i-PS phase in the blend is higher than the corresponding percent of i-PS (i-PS greater than or equal to 30%) while its crystallinity is less than the percent of i-PS (i-PS less than or equal to 10%). Effect of miscibility and solvent on their crystallization has also been discussed.