Oleic acid modified nano-copper was synthesized,and the tribological properties of lubricating oil with nanocopper under different current carrying conditions were investigated on a fourball tribotester with the current carrying capacity.Scanning electron microscopy (SEM),white light interferometer (WLI) and X-ray photoelectron spectroscopy (XPS) were used to analyze the worn surface of steel ball,and the tribological mechanism of nanocopper under currentcarrying conditions was discussed.The results show that the current carrying conditions enhance the antiwear and friction reducing effect of nano-copper under the appropriate amount of nano-copper.Under the current carrying condition,the content of copper element on the worn surface of steel ball is higher,and it exists in the form of Cu and CuO.The conclusion is drawn that nanocopper has an electrophoretic movement under the currentcarrying condition,the electrothermal effect of current-carrying conditions promotes the softening and smearing of nanocopper,and the currentcarrying condition is helpful for nano-copper to participate in tribochemical reaction