In order to improve the anti-wear and friction reducing properties of water-based lubricant,an environment-friendly oleic acid-based extreme pressure water-based lubricant additive (OWELA) containing extreme pressure elements P and N was synthesized.Fourier transform infrared (FTIR) and 1H nuclear magnetic resonance (1H NMR) were used to characterize the intermediate of Polymerized P-N dihydric alcohol (PG) and OWELA.The lubrication performance of OWELA was studied with a four-ball friction tester,the wear surface of the ball was analyzed by using scanning electron microscopy and X-ray photoelectron spectroscopy,and the lubrication mechanism was further analyzed.The results show that compared with PG,OWELA can significantly reduce the friction coefficient and wear scar diameter of water,which can increase the maximum non-seizure load of pure water by 3.5 times,and has good anti-corrosion performance.The excellent tribological properties of OWELA are attributable to the high-strength chemical reaction film formed by highly active extreme pressure elements P and N with the metal,and the physical adsorption film formed by fatty acid molecules on the metal surface,which play a synergistic role.