Abstract: The composites of multiwalled carbon nanotubes/polyamide 6 (MWCNTs/PA6) were fabricated by liquid blending method. The effects of the modification methods and contents of MWCNTs on the thermal and crystal properties of MWCNTs/PA6 composites were studied. The composites were characterized by FESEM, FTIR, DSC, XRD and TG. The results show that the thermal stability of PA6 can be improved through adding MWCNTs, especially amino-functionalized MWCNTs (d-MWCNTs). When the mass fraction of d-MWCNTs reaches 7.5%, the crystallization degree of the MWCNTs/PA6 composites is improved from 48.09% to 56.62% and the entangled degree among polymer macromolecules is the lowest.