Abstract: PA66/MMT nanocomposites were prepared by direct melt blending.XRD results proved that intercalation structure had been achieved.XRD and DSC analyses indicated that the crystallinity and supercooling of nanocomposites decreased and the size of the crystallites was also reduced.The intercalation of mortmorillonite into PA66 played a role as a nucleating agent for crystallization of PA66.The addition of MMT could improve the decomposition temperature,storage modulus and glass temperature of PA66 according to TGA and DMA analyses.