Poly(lactic acid) (PLA) and maleic acid anhydride end-capped poly(propylene carbonate) (PPC-MA) were melt blended with or without transesterification catalyst tetrabutyl titanate (TBT). The gel permeation chromatography (GPC), dynamic mechanical analysis (DMA) and differential scanning-calorimetty (DSC) results indicated that the addition of TBT promoted the transesterification and the transesterification degree increased with increasing the TBT content. The scanning electron microscopy (SEM) photographs showed that the PLA/PPC-MA/TBT could be plastic stretched deeply under tensile stress. Moreover, PPC-MA was more active than PLA in-the catalytic transesterification and the weight percent of PPC-MA had obvious effects on the mechanical properties of the blends. The tensile toughness of PLA/PPC-MA blends was significantly improved with the addition of TBT when the PPC-MA content was higher than 50 wt %.