The carbon films exhibit a variety of useful properties such as a hardness approaching that of a diamond, transparency,a smooth surface morphology,wear resistance and chemical inertness,and were widely applied in the fields of mechanics,electronics,optics,and magnetic,and so on. Experimental studies to obtain high quality hard carbon films were conducted using a Mirror-Confinement-type Electron Cyclotron Resonance (MCECR) plasma sputtering method.The carbon films with 40 nm thickness were deposited on Si by sputtering the carbon target with Ar +.The structure of carbon films was analyzed using the X-ray photoelectron spectropscopy (XPS) and high-resolution transmission electron microscopy (HRTEM),the tribological properties were measured using the Pin-on-Disk tribometer,and the nanohardness was measured using the nanoindenter.The effect of substrate bias on the structure,tribological properties,and nanohardness of carbon film was studied in detail,and the best substrate bias was obtained.