Abstract: In this study, Co-Al layered double hydroxide (Co-Al LDH) interlayered with carbonate ions was firstly synthesized from urea pyrolysis method. Then, based on HCl-NaCl mixed solution method and anion exchange method, Co-Al LDH interlayered with other anions were prepared and their chemical composition, crystal structure and morphology were subsequently examined. By using an SRV-1 ball-on-disk tribometer, the tribological properties of PAO-8 doped with different LDH with the same concentration of 0.1% were characterized. It was proved that the tribological properties of PAO-8 were obviously improved just by adding a small amount of LDH. Interlayer anions had a great influence on the friction-reduction and anti-wear properties.