The borate lanthanum modified by oleylamine (OAmLaBO3) was prepared by surface modification technology and direct precipitation method.The morphology,structure and chemical composition of OAmLaBO3 nanoparticles were characterized by various instruments and equipment.The tribological properties of OAmLaBO3 were evaluated in mineral oil of liquid paraffin (LP) and synthetic ester oil of diisooctyl sebacate (DIOS),and the tribological effect and mechanism of the OAmLaBO3 nanoparticles were suggested.Results show that the synthesized borate lanthanum has certain friction reducing and antiwear properties in both LP and DIOS based oils.The friction reducing of OAmLaBO3 in LP is significant,while the antiwear property of OAmLaBO3 in DIOS is prominent.The main reason is that the polarities of LP and DIOS are different,and the adsorption of small organic molecules decomposed by OAmLaBO3 on the friction surface during the friction process is different,resulting in a different mechanism of friction reduction and antiwear.