Polyblends of PLA/POE-g-MAH/TAIC were prepared by melt blending and gamma-rays irradiation. Mechanical characterization, gel extraction and scan electron microscope (SEM) were employed to research the irradiation effect of the blends. The results indicated that PLA/POE-g-MAH/TAIC blends could be in situ compatibilized by irradiation and the mechanical properties were enhanced. When irradiated at a absorbed dose of 30 kGy, the notched impact strength of the blend with the weight ratio of 50/50/3 was obviously improved to 20.8 kJ/m,2, which was about 2.5 times of the value without irradiation. The conclusions of scan electron microscope (SEM) and gel extraction were agreed with changes of mechanical properties. Since a new copolymer comprising both chain segments of PLA and POE was formed at the interphase area at certain absorbed dose, the compatibility of the blend was improved, and obvious features of ductile fracture was confirmed by lots of yield deformation when the samples were impacted.