Abstract: The tribological performance of steel/PTFE contact lubricated by ionic liquids(BA-DBP, BMIM-DBP, L-P104) was evaluated on an Optimal SRV-IV oscillating friction and wear tester. In addition, the conventional lubricant poly α-olefin(PAO) was selected as reference lubricant. Meanwhile, the dry friction tests were carried out under the same test condition. The worn surfaces of the PTFE lubricated by different ionic liquids were analyzed by a JSM-5600LV scanning electron microscope and a PHI-5702 multifunctional X-ray photoelectron spectrometer. As a result, the tribological properties of three ionic liquids were similar to that of PAO under the variable load and frequency condition. Nevertheless, the ionic liquids performed better lubricating behavior than conventional lubricant PAO under constant load and frequence test condition. The reason was that the tribochemical reactions between the PTFE substrates occurred and active elements of N, P and O in the lubricant molecule during the friciton tests and the compound boundary lubricating film on the friction surfaces effectively restrained the direct contact of the friction pair. Moreover, the lubricating property of the compound film was superior to that formed by the PAO.