Abstract: In this paper, we present the classification and roles of lubricant additives. When applied as lubricant additives, nanoparticles show special and excellent tribology properties. Therefore, we further summarize main types of nano lubricant additives and discuss action mechanism of nanoparticles during friction process. In addition, some analyses about the research focus and development trend of nanoparticles in lubricants are put forward combining with our work.