Abstract The tribological properties of Al₂O₃/WS₂ composite lubricant were examined by using a ball-on-plate reciprocating sliding wear test configuration utilizing PAO₆ base fluid and oleic acid as surfactant. The morphology and chemical composition of the wear tracks were examined by using a scanning electron microscope and a x-ray energy dispersive spectrometer. It was found that the coefficient of friction was reduced by 46.6% after adding 0.5 wt% Al₂O₃/WS₂ composite particles. The wear width and wear depth were reduced by 37% and 59.6% after adding 3 wt% Al₂O₃/WS₂ composite particles. In orthogonal tests, it was proposed that the best tribological performance of Al₂O₃/WS₂ composite lubricant could be achieved while using the normal load of 50 N, frequency of 2 Hz and temperature of 65 °C. Frequency could be considered as the primary factor affecting the tribological properties of compsite lubricant. The excellent lubricating performance could be attributed to the formation of WS₂ tribo-film with low shearing resistance, and a portion of the Al₂O₃ particles were embedded by external force to prevent surface contact between the steel ball and brass plate.