As a classic film-resistant coating, DLC film is widely used in the field of impact wear. The impact wear properties of DLC films with different thicknesses (1.1 μm thin DLC film and 7.9 μm thick DLC film) on various substrates (9Cr18 and TC4) were evaluated. On the TC4 substrate, the experimental results demonstrate that the thick DLC film offers obvious damage and serious impact wear, but the thin DLC film exhibits reduced deformation and wear. On the 9Cr18 substrate, both thick and thin DLC films work successfully in protecting the substrate. The failure mechanisms of the two DLC films are mainly abrasive wear (thin DLC film) and adhesive wear (thick DLC film). The thin DLC film with the highest hardness, toughness, and adhesion represents the best protective coating for impact dynamic load applications examined, regardless of whether the substrate is soft or hard.