Diamond-like Carbon (DLC) films were deposited on silicon substrate by radio frequency plasma enhanced chemical vapor depositing technology with methane as source gas.The tribological performances of the DLC films against with Al2O3 ball under air and 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim]BF4) ionic liquid lubrication were tested by reciprocating ball-on-disc tester.The wear tracks,bonding structure of wear tracks and wear rates were investigated by measuring microscope,X ray photoelectron spectroscopy (XPS) and 3D surface profiler,respectively.The results show that the DLC film has a lower friction coefficient with ionic liquid under low load,and the friction coefficient is stable with the load increasing.This may be attributed to the boundary lubricant films physical absorbed between contact interfaces,and the boundary-film formed by ionic liquid reduce the wear of DLC films obviously.