The cracking behavior of spherulites in melt-crystallized poly (l-lactic acid) and poly [(R)-3-hydroxybutyric acid] was investigated in an isothermal crystallization process. Layered spherulites with dual T (c) were prepared under gradient cooling conditions. As T (c) decreased the crack density reduced obviously, while width and depth of the cracks increased. A comparison of the effects of crystallization temperature (T (c)) and spherulite size on cracking behavior in spherulites was present for the first time. Cracks were found to be more sensitive to T (c) than spherulite size. Cracks were healed with a thermal treatment and the process was fully reversible. The crack positions were closely depended on the crystalline lamellae alignment set up at T (c).