Abstract: The effect of maleic anhydride (MAH) grafted POE (Polyolefin Elastomer) on the morphology, microstructure and mechanical properties of PA66/POE blends was investigated by means of SEM, TEM, DSC and mechanical properties measurement. The results show that the grafted product (POE-g-MAH) can improve the miscibility between PA66 and POE, decrease the particle size of dispersion phase and obviously increase the charpy notched impact strength of these blends. It was found that there are more regular structures in the dispersion phase elastomer particles of PA66/POE-g-MAH blends than those in the particles of PA66/POE blends; the dispersion phase elastomer particles of PA66/POE-g-MAH blends can accelerate crystallization of the matrix, and increase the crystallization temperature T_cd and the crystallization enthalpy ΔH_c of the PA66 matrix. In the case when the brittle-ductile transition of the blend occurs, the accelerating action reaches the strongest, and the values of T_cd and ΔH_c reach maximum; the faster the cooling rate of the melt specimens, the stronger the accelerating action of the particles.