Abstract: Many important functions of spacecraft achieve relying on precise angle-contactball bearings,so their properties must accord with the strict demands and it is in urgent needto know the failure mechanism of the lubrication,Lubrication performances of sputtered solidMoS2 film-lubricated ball bearing pairs of type C6205 were evaluated using life test,and thenthe topography and compositions of the working surfaces were systematicly examined bySEM,EDAX and AES. The mechanism of the solid lubrication failures is considered as fol-lows:repeated rolling of balls on sputtered MoS2 films in the inner and outer races leads tosurface fatigue wear, with which accompanying obvious sliding is enabled to induce the abra-sive wear, meanwhile the ball surfaces are scratched by glass fiber in the cage and metallicwear particles are produced and so those results aggravate abrasive wear of the thin solid MOS2film;when the MoS2 film was thinned to a certain degree,followed by bubbles and fatiguemicrocrack occurred and developed,pilling-up appeared in micro-areas and so the frictiontorque enlarges gradually;as the MoS2 film is exhausted and the substrate is increasingly pitted,an oscillation occurs and a noise is heard when the friction torque enlarges to some extent.