Three multi-lubricating additive unites composed of poly(ionic liquid)s (PDS-P11, PDS-P13, PDS-P15) were prepared easily via the copolymerization of stearyl methacrylate and 2-(diethylamino)ethyl methacrylate in different ratios and then protonation with bis(2-ethylhexyl)phosphate. When they were investigated as potential multifunctional lubricant additives of synthetic oil PAO10, all of them could improve the corrosion resistance, viscosity, viscosity index, friction and wear reduction properties of PAO10. In particular, mixing 5 wt% PDS-P13 with PAO10 affords a clear and well dispersed lubricant system with a viscosity index of 163, which could reduce the coefficient of friction and wear volume of PAO10 by 56 % and 97 %, respectively. More importantly, the resulted PAO10 blends bear excellent lubricity under high temperature (100 °C) and a high extreme bearing capacity of 1600 N. The lubrication mechanism studies results revealed that a buffer protective film was formed on the steel substrate surface via physical adsorption and complex tribochemical reaction, which provided excellent protection to the rubbing pairs.