Abstract: Based on the antioxidant mechanism of α-tocopherol and the formation process of molecular ion M +· under FAB conditions, the relationship between the FAB-MS and antioxidative effect is discussed,and it is found that they all involve a one-electron transfer. Cyclic Voltammogram (CV) is carried out to get the oxidation potentials (Epa) which can reflect the antioxidative effect of compounds. Furthermore, the ratios of I(M +·)/I( +) evaluated from the FAB-MS spectra are correlated with the Epa, the ratios are higher, the Epa are lower. Therefore, it is demonstrates that the intensity of M +· in FAB-MS spectra can reflect the antioxidative effect of compounds to some extend, FAB-MS techniques can provide a useful clue to screen the antioxidative activity of compounds.