Abstract: In order to improve the tribological performance of PFPE grease in vacuum,W-doped flower-shaped MoS₂ powders were prepared by hydrothermal method.X-ray diffractometer,scanning electron microscope and transmission electron microscope were used to characterize the structure and morphology of the MoS₂powders.The effect of the W-doped flower-shaped MoS₂content in the PFPE grease on the vacuum tribological performance were tested using a vacuum fourball friction tester.The surface of the wear scars were characterized by optical microscope,surface profiler,scanning electron microscope and X-ray photoelectron spectroscopy.The results show that the W-doped flower-shaped MoS₂crystal form well to the Mo(W)S₂crystal,and flower-shaped stacking of nanosheets combine to form the W-doped flowershaped MoS₂structure.The vacuum tribological performance of PFPE grease is improved as the amount of W-doped flowershaped MoS₂powder increase.W-doped flower-shaped MoS₂can form a transfer film on the friction surface through physical adsorption and tribochemical reaction with metal.And it can be transferred to the friction surface together with the fluorocarbon-based thickener in PFPE grease,which produces a synergistic lubrication effect.