In order to investigate the effect of Zinc Oxide particle size on the properties of nitrilebutadiene rubber (NBR),the samples of NBR filled with conventional ZnO (c-ZnO) and nano-ZnO (n-ZnO) were prepared,the resistance to crude oil swelling was tested,and the friction and wear behaviors were studied using computercontrolled reciprocating wear tester under crude oil lubrication.The morphology of worn surface was measured using SEM.The results show that,compared with NBR sample containing c-ZnO,the NBR sample containing n-ZnO has good resistance to crude oil swelling,smaller friction coefficient and wear volume under the crude oil lubrication.According to the SEM analysis,Schallmach pattern appears on the wear surface of the two samples under crude oil lubrication,which shows typical viscoelastic friction and wear characteristics,however,the wear degree of the sample containing n-ZnO is better than that of the sample containing c-ZnO.The NBR containing n-ZnO has a higher crosslinking density,which can prevent effectively oil molecules invading into the bulk of NBR,reduce the damage of external mechanical stress to the wear surface,thus showing excellent tribological properties.