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Poly(butylene adipate) (PBA) is a biodegradable polyester with polymorphic crystal structure.Our previous work has reported that changing the temperature (Tc) of isothermal crystallization via homogeneous nucleation results in the formation of polymorphic crystals.PBA with α or β crystal structures is formed at Tc above 32oC or below 27oC, respectively, while PBA with mixed α and β crystal structures is formed at Tc between 27oC and 32oC.It was found that the biodegradation rate of PBA depends on its polymorphic crystal structure.In this work, the effects of heterogeneous nucleating agent multimethyl-benzilidene sorbitol (TM6) on crystallization and polymorphic crystal were studied.It was found that the TM6 plays the role of heterogeneous nucleation for PBA crystallization, and the addition of TM6 is favorable for the formation of PBA α-form crystals, resulting in the morphological changes from spherulites to interpenetrated fibrils.The results of enzymatic degradation revealed that the interpenetrated fibrils are resulted from the PBA crystals induced by TM6 fibrils.Based on these results, the PBA microspheres composed of nanofibers were prepared by heterogeneous nucleation and double emulsion solvent evaporation method.These nanofibrous microspheres showed the potentials as microcarriers for cell growth.