Abstract: Ti, Si doped diamond-like carbon films were deposited on Si substrate by middle-frequency (MF) magnetron sputtering technique. The tribological properties of the film were investigated on a ball-on-disk tribometer in different atmosphere environments. The worn surfaces and transfer layer were observed and analyzed using a scanning electron microscope and Raman microscope. The friction and wear mechanisms of the film were also discussed. In vacuum or nitrogen environments, the wear rates of the film were much small, and the wear mechanism was mainly abrasive wear. In oxygen or high relative humidity air environments, the film exhibited much high friction coefficients and wear rates, and the wear mechanism was mainly adhesive wear. In low relative humidity air, the friction coefficient reached the minimum value. The film displayed a mixed wear mechanism of abrasive wear and adhesive wear. Raman spectra reveal that transfer layer appeared the tribochemical processes of friction-induced graphitization and dihydrogenated reaction of C=C bonds of polyacetylen chains included into diamond-like carbon film.