Abstract: Carbon nanotubes were modified by non covalent bond with trimethyl-1-propanaminium iodide (FC-134) which was a water soluble cationic surfactant. The modified carbon nanotubes/natural rubber composites were prepared with the liquid phase method. The effect of the modified carbon nanotubes on the properties of the composites was studied. The results show that the modified carbon nanotubes are stable in water. Payne effect shows that the interaction between carbon nanotubes is weakened, and the carbon nanotubes-rubber interaction is enhanced. And the carbon nanotubes are uniformly dispersed in the composites as the result of rubber processing analyzer (RPA). When compared to the pristine carbon nanotubes/natural rubber latex composites, the tear strength and tensile strength are increased by 65% and 29%, respectively.