A phosphate ester containing nitrogen from methyl oleate was synthesized via epoxidation-reaction, epoxy-group nucleophilic ring-opening reaction and esterification, through chemical modification in double bond of methyl oleate molecule. The chemical structure of synthetic product was characterized by Infrared-spectroscopy. The tribological performance of synthetic product in rapeseed oil was investigated by four ball friction test machine. Results showed that, after chemical modification, the anti-wear ability and extreme-pressure performance of methyl oleate were improved significantly. The P B value increased 520-1323 N enhancing 154.42%, while P D value increased 1236-3089 N enhancing 149.92% and WSD decreased 0.56-0.39 mm dropping 23.53%. Results also indicated that the synthetic product could be used as a good extreme-pressure and anti-wear lubricant additive in the rapeseed oil. Finally, indicate that the phosphate film generated in the friction surface through tribochemical reaction is the main reason for tribological performance improving of the chemical modified methyl oleate.