In order to evaluate the effects of common antioxidants in oils for metal working,the antioxidant properties of three types (four kinds) of antioxidants in animal oils (refined lard oil) which were chosen to be the base stock were studied by TGA and PDSC,together with aging tests at different temperatures.The test results indicate that the antioxidants are effective in retarding oxidation,though the effects of different types of antioxidants are different from each other.The antioxidant properties of phenols are better than that of anilines and thioethertypes at lower temperature.While thioethertypes are better than others in inhibiting oxidation at high temperature.To protect the oil products effectively,it is necessary to compound one type of antioxidants with other types in practice for more complicated working conditions.