The effects of antiwear additives on tribological behavior of vegetable oils was studied. It has carried out antiwear additives, TCP and DBP in vegetable oils were formulated and tested the antiwear performance, surface analysis of worn balls and thermal degradation. The new additive, DBP showed excellent antiwear performance compared with conventional additive TCP under high speed and temperatures. The DBP additive was found to be an effective antiwear additive in vegetable oils.