Nano tungsten disulfide has excellent lubrication performance,but its easy agglomeration in lubricating oil affects its anti-wear and friction reduction performance.To improve the anti-wear and friction reduction performance of nano WS2,a phosphate ionic liquid was added to WS2 nano lubricating oil,and its frictional properties were tested using four-ball friction tester.XPS,EDS,and electron microscopy were used to characterize the worn surface of the steel balls.The results show that although the friction coefficient of nano lubricating oil is slightly increased after adding ionic liquid,compared to the base oil,ionic liquids can still reduce the friction coefficient by a maximum of 28%,and can significantly reduce the wear scar diameter,with a maximum reduction of 44%.In the friction process,the ionic liquid reacts with WS2 to generate PW,which acts as a catalyst to accelerate the oxidation reaction in the friction process,and the generated compound acts as a chemical friction film to reduce wear and improve the anti-wear and friction reduction performance of lubricating oil.