In this work, the feasibility of using planetary ball milling for coating bearing balls with a self-lubricating film was investigated. Bearing balls with appropriate amount of MoS2 powder were put into vacuumed stainless steel vials and ball milled. With proceeding of ball milling, thickness of the self-lubricating film increased at first and then decreased. X-ray diffraction (XRD) and X-ray photoelectron spectrum (XPS) results revealed that the surface of the self-lubricating film was MoS2 and the inner region was a mixture of iron molybdenum alloys (Fe3Mo, FexMoy), MoS2 and FeS. Friction coefficient between the self-lubricating film and bear steel was 0.06~0.1.