Abstract: In order to improve the fretting wear resistance of TC4 titanium alloy, diamond-like carbon (DLC) films were deposited on the surface of TC4 titanium alloy by unbalanced magnetron sputtering (UBMS) technique. The fretting friction and wear behaviors of DLC film against GCr15 steel ball were studied using a ball-on-flat contact. Under different normal loads and displacement amplitudes, the slip regime and wear mechanism of DLC film were studied with the running condition fretting map(RCFM). The characterization and fretting friction and wear performance of DLC films were carried out by means of atomic force microscopy, nanoindentation, laser Raman spectroscopy, three-dimensional optical profilometer, laser confocal microscope, field emission scanning electron microscope and SRV-V fretting friction and wear tester. The damage mechanism was revealed through the analysis of fretting maps, dissipated energy, the morphology and chemical composition of wear track. The results showed that the displacement amplitude and normal load had great effect on the fretting mode and damage mechanism. The mixed slip regime (MSR) was dominant at the displacement amplitude of 25 μm. On the other hand, the slip regime was gross slip regime (GSR) at the displacement amplitude of 100 μm. The abrasive wear was the main damage mechanism of DLC film under small displacement amplitude, whereas under larger displacement amplitude the wear mechanism of DLC film was mainly adhesive wear. In short, the good fretting wear performance of DLC film in dry friction lies in its excellent mechanical properties and self-lubricating properties.