Au/Multiwalled Carbon Nanotubes(Au/MWCNTs) composites were synthesized by a chemical adhesion method.The composites were characterized by X-ray diffraction,UV–vis absorption and transmission electron microscopy,which demonstrated that Aunanoparticles with an average diameter of about 6 nm covered the MWCNTs surface.The third-order optical nonlinearities of MWCNTs and Au/MWCNTs composites were investigated using picosecond Z-scan technique at 532 nm.The third-order nonlinear susceptibility χ(3) of Au/MWCNTs composite was calculated to be 1.89×10-12 esu,which was 2.6 times larger than that of MWCNTs.