Ion beam assisted deposition offers a novel and unique process to prepare diamond-like carbon (DLC) films at room temperature with particularly good interface adhesion. This advantage is explored to deposit highly wear resistant DLC coating on AISI 52100 steel. Various bombarding species and energy are examined to optimize the process. Infrared, Raman, Auger electron spectroscopy spectra, and hardness measurements are used to characterize the structure and properties of DLC films. The friction and wear behavior of DLC films are systematically investigated by performing extensive experiments in different testing styles. It is disclosed that by means of a dynamic mixing of atoms in interfaces, a pure metal intermediate layer can tremendously improve the tribological properties of DLC films on 52100 steel. The results are optimistic and may lead to useful applications.