Antimony (Sb) is an element of growing interest. Its toxicity and mobility are strongly influenced by redox processes. Pyrite (FeS₂) is the most abundant natural sulfur mineral in the earth’s crust. Pyrite is also associated with stibnite. Simultaneously, Some studies have reported that Sb(III) can be oxidized to Sb(V) both in solution and on pyrite surfaces in oxic condition. The pyrite-induced hydroxyl radical (·OH) and hydrogen peroxide (H₂O₂) are the main oxidants for Sb(III) oxidation. However, pyrite is thermodynamically unstable and can be oxidized in aerobic environments. It has been proposed that pyrite oxidation results in the formation of an oxidation layer on its surface. The nature of the oxidation layer on pyrite will determine the reactivity of weathered pyrite in aqueous solutions. Our interest here is the surface phase will determine how weathered pyrite might oxidize Sb(III). In this research, pyrite was exposed to air at room temperature for 1 week and the product was named SOP(O₂). Aqueous pyrite oxidation experiments were also performed. In this step, pyrite samples were immersed in air-saturated water (pH=3, 5 and 7) for 1 week and SOP(H₂0) were obtained. Sb(III) oxidation in pyrite suspension was investigated at pH =3, 5 and 7 under oxic condition with 2μmol/L Sb(III) and 0.5 g/L pyrite. Our study showed that the oxidation efficiencies of Sb(III) by SOP(O₂) were enhanced compared with by pyrite in all conditions. But the efficiencies of Sb(III) oxidation by SOP(H₂0) were greatly restrained at pH=3,5 and 7. We found that the ferric and ferrous (hydr)oxides were formed on the surface of SOP(O₂). Besides, pyrite oxidation in water phase results in the formation of an Fe-hydroxide or Fe-oxyhydroxide layer on the surface. Thus oxidation layer on pyrite has great influence on the efficiency of Sb(III) oxidation.