In the cylinder liner-piston ring friction pair,when the piston is zero speed at the top and bottom dead center,it is difficult to form an oil film,and under the high temperature working condition of the cylinder,the oil film in other parts will also be destroyed,resulting in increased friction power consumption and wear of the cylinder liner-piston ring.The use of high quality lubricating oil is an important means to improve the lubrication and friction characteristics of cylinder liner-piston ring.Modified nano-hexagonal boron nitride (h-BN) particles were prepared and dispersed of them in different mass fraction into polyα-olefin (PAO10) base oil.R-tec friction and wear testing machine was used to carry out reciprocating friction tests under different loads,and the friction coefficient,wear volume,wear surface of cylinder liner,wear elements and three-dimensional morphology parameters were observed.The influence of modified nano h-BN additive on tribological properties of cylinder liner materials and the friction reducing and anti-wear lubrication mechanism were studied.The results show that the addition of modified nano h-BN additive can significantly reduce the friction coefficient of cylinder liner-piston ring friction pair and reduce the wear amount.Under the working condition of 50 N and 3 Hz,the addition of 0.25% mass fraction additive can reduce the friction coefficient by 33.87% and the wear volume by 23.32%.Under the action of load and friction heat,nano h-BN additive can form a friction protective film on the wear surface,improve the surface roughness of the cylinder liner,create an excellent lubrication environment,and enhance its tribological properties.