Abstract: Oleic diethanolamide phosphate (OEAP) was synthesized with oleic acid，diethanolamine and phosphorus pentoxide and its structure was characterized by means of IR spectroscopy. The impacts of OEAP as an additive on the biodegradability, corrosiveness, antiwear and friction-reducing ability of HVI350 mineral lube base oil were investigated. Test results indicated that OEAP additive could effectively enhance the biodegradability, load carrying capacity and friction-reducing ability of HVI350 mineral oil. Furthermore, the corrosion resistant of HVI350 lube oil was also improved by OEAP additive.