This paper investigates applicability of polysiloxane/MoS₂ lubricating coatings in low-earth orbit (LEO). Results show that wear resistance of the polysiloxane lubricating coatings is related to R/Si value and epoxy group of the epoxy-functionalized polysiloxanes resin. The prepared polysiloxane lubricating coatings exhibited better wear resistance than existing organic coating due to the synergistic effect of low surface energy polysiloxane and MoS₂. Furthermore, the polysiloxane coating achieved excellent AO resistance ascribe to the generation of SiO₂ protective layer. The thickness of SiO₂ layer was only 60 nm, which has no effect on vacuum tribological
properties of the polysiloxanes lubricating coating. After AO irradiation, the polysiloxane lubricating coating maintained a low friction coefficient and excellent wear resistance under the vacuum condition.