Four oxidants, NaClO, KMnO4, K2Cr2O7, and H2O2, were used to promote the flotation separation of pyrite (FeS2) from arsenopyrite (FeAsS). Ore flotation results indicate that H2O2 has the best selectivity for the As-S separation. When H2O2 is used, the As content in pyrite concentrate decreases from 2.27% without addition of H2O2 to 1.11% with H2O2 dosage of 900?g/t, and the pyrite recovery is still high (86.58%). NaClO, KMnO4, and K2Cr2O7 have poor selectivity for the As-S separation. Cyclic voltammetry measurements by using mineral microelectrodes indicate that H2O2 shows selective oxidation effect on arsenopyrite while other three oxidants have no selective oxidation effects on arsenopyrite and pyrite. In the presence of dixanthogen coating on the mineral surface, all the four kinds of oxidants can oxidize dixanthogen to a certain degree. Moreover, the collector coatings on arsenopyrite surface are oxidized more easily than on pyrite.