Ultrafine serpentine powder with average particle size of 1 μm was prepared with highenergy ballmilling method.Serpentine powder was added to the PAO10 base oil with oleic acid according to mass ratio of 2∶1.The friction and antiwear properties of the lubricant additives were investigated by fourball machine, and the three dimensional morphology of worn surface was characterized by the White Light Interferometers, and the elements of worn surface were analyzed with EDAX.Results indicate that compared to serpentine powder, the compound additives consisted of serpentine powder and oleic acid can reduce friction and wear more efficiently.A tribofilm is formed on the worn surface with the presence of Si, Mg elements under the compound additives of serpentine powder and oleic acid, while the tribofilm cannot be formed on the worn surface lubricated under the single additive of serpentine powder.It is because that the oleic acid as a dispersant can absorb metal wear particles produced in the friction process, and disperse them into lubricant, so the abrasive wear is reduced on worn surface.The organic tribofim of oleic acid is absorbed onto the particle surface of serpentine, which improves disperse of the particles in the base oil.