Abstract: The coefficient of friction of hydrogen-free DLC/Cu system is high and difficult to tailor, in addition, it is a problem to reduce the frictional coefficient of DLC/copper so as to control its frictional properties. The tribological properties of copper against DLC films with different hydrogen content were studied through friction experiment and simulation, the effects of hydrogen atoms on friction interface improving were also discussed simultaneously. The results show that friction interface was of great importance to tribological performance of DLC/Cu system, and hydrogen atoms played a role in tailoring the friction interface by reducing adhesion at interface. The interaction at interface can be changed by doping modified elements (hydrogen) into DLC film so as to improve the tribological performance of DLC/Cu system. The research ideas and results can provide reference for improving the lubrication properties of DLC/Cu system.