Select mineral oil, partial synthetic oil, full synthetic oil as automatic transmission fliud’s base oil,the different extreme pressure antiwear additives of T203, T307 and T306 were added into four different base oil combinations,the tribological properties of different extreme pressure of antiwear additives in the base oil were studied through four ball machine.The experimental results show that,in the separate base oil,T203 and T307 have the best effect on the antiwear performance of mineral oil,while The antiwear property of T306 with different additions in different base oils is similar.In the area of extreme pressure performance,T203 and T306 have the best extreme pressure sensitivity in the full synthetic oil,T307 has little difference in extreme pressure performance in different base oils.In partial synthetic oils,the proportion of synthetic oil has different effect on the friction property of base oils.Compared with the single antiwear additive,the twoadditive combination can not significantly improve the antiwear property of base oils.