The nano/micro structured Cu/Graphene oxide composites were prepared by in situ reducing CuSO4 in graphene oxide solution. The transmission electron microscopy (TEM),field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) were used to character their structure. The composites were modified and added into liquid paraffine to investigate their tribological properties by four ball wear tester. The results show that the diameter of Cu nano particles is not more than 100 nm. Under the experimental conditions of 392 N,1 450 r/min and 30 min,the friction coefficient of liquid paraffine is decreased by 33% as 2.0% composites added into base oil, and the wear scar diameter is reduced by 25% as 0.5% composites added into base oil.