Abstract: The effect of four amide compounds as additives in liquid paraffin on the friction and wear behavior of steel-steel and steel-aluminum alloy systems was investigated with a four-ball machine and an Optimol SRV friction and wear tester, respectively. The worn surfaces of the 2024Al alloy block were analyzed by means of X-ray photoelectron spectroscopy (XPS). As the results, the four amide compounds as additives help to decrease the wear rate and friction coefficient of steel-steel frictional pair; while acrylamide and acetamide show better anti-wear and friction-reduction ability for the steel- aluminum frictional pair. XPS analysis of the worn surface of Al alloy block indicates that acrylamide as an additive in liquid paraffin functions to decrease the friction and wear of steel-aluminum pair by forming a complex protection film on the worn surface of the Al alloy.