Abstract: Ni-Al layered double hydroxide (LDH) was synthesized by urea pyrolysis method. The dibutyl phosphate anion interlayered LDH (LDH-DBP) and diisooctyl phosphate anion interlayered LDH (LDH-OBP) were prepared by the phosphate interlayered modification with the anion-exchange method. Their chemical composition, crystal structure and morphology were detected by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetry analysis and transmission electron microscopy. Furthermore, the tribological properties of PAO-4 using LDH, LDH-OBP and LDH-DBP as additives were characterized on the SRV-IV tribometer. The experiment results indicate that the modified additives performed excellent tribological properties under high load (200 N). The lubrication mechanism was ascribed to the synergy between the flake adsorption of LDH and the tribochemical reaction of phosphate with metal substrates．