In order to improve the tribological properties of lithium-based grease,lithium greases modified by different content of nano-CuO were prepared. The nano-CuO particles were characterized by 3H-2000PS2 specific surface and micropore analyzer,the effect of nano-CuO addition on the tribological properties of lithium-base grease was analyzed by four ball friction and wear tester,and the wear scar morphology of steel ball was analyzed by SEM and 3D morphology analyzer. The results show that when the weight fraction of nano-CuO is 0. 60%,the lithium-base grease has the best anti-wear and friction reducing effect,and the friction coefficient and wear scar diameter are 24% and 12% lower than the base grease,respectively. Under a certain addition,nano CuO can repair the worn surface. When lubricated by the grease containing 0. 60% weight fraction of nano copper oxide,the worn surface has low surface roughness and less furrows,showing the best anti-wear performance.