This study explored the efficient removal of As(III) by Fe(III)-amidoximated PAN (Fe(III) AO PAN) in the presence of H2O2 through simultaneous oxidation and adsorption. It presented that As(III) could be oxidized to As(V) efficiently in the pH range 3–9 within a short time. At the same time, the oxidized As(V) was adsorbed by Fe(III)-AO PAN. The effect of pH value, H2O2 concentration, Fe(III)-AO PAN amount, and coexisting anions on the As(III) oxidation and removal were investigated in detail. Dynamic adsorption on fixed column was also studied. Arsenic removal efficiency including As(III) and As(V) could be achieved (95.2%) by the simultaneous oxidation and adsorption process at the following optimal conditions: pH = 6.5, dosage of Fe(III)-AO PAN = 2.5 g/L, H2O2 = 100 mg/L, initial concentration of As(III) = 5 mg/L. Dynamic adsorption on fixed column demonstrated that As(III) in simulated groundwater could be efficiently removed from 500μg/L to <10 μg/L within 130 bed volumes (BV).