AbstractTo improve the toughness of polylactic acid (PLA), in this research, a tough polymer polycaprolactone (PCL) was combined with PLA to prepare blends, and a compatibilizer of glycidyl methacrylate grafted PLA (PLA‐g‐GMA) was produced to enhance the compatibility of PLA/PCL blend. Compared with PLA/PCL blend, the compatibilized blend exhibited a lower melting temperature and greater thermal stability. The tensile test indicates that the addition of compatibilizer greatly improved the toughness of the PLA/PCL blend. Particularly, the elongation at break of PLA/PCL blend with 6 wt% PLA‐g‐GMA increased to 370% and reached about 66 times of neat PLA. In addition, compatibilized blends have good shape memory performance. The research provides a simple and feasible method to overcome the brittleness of PLA, supplying a new strategy to modify PLA.