Abstract: WS_2/Ag nanocomposite films were deposited by magnetron sputtering on titanium alloy substrate.The morphology and microstructure were characterized by scanning electron microscope,transmission electron microscope and energy dispersive X-ray spectroscope.Friction and wear behavior of the WS_2/Ag composite films were investigated on a ball-on-disc tribometer in vacuum and in humid air.The as-deposited composite films were mainly amorphous,and nanoscale crystalline Ag phase distributed in WS_2 matrix enhanced the adhesive strength between the film and substrate.Although the friction coefficient of the nanocomposite film was slightly higher that of WS_2 film,the wear resistance and durability of the WS_2/Ag film were improved significantly in humid air. The WS_2/Ag nanocomposite film exhibited more stable friction state as compared to WS_2 film in different environments.