The Mn loaded ACF (ACF-Mn), prepared by impregnation method combined with activation method under high temperature, can be used to adsorb the low concentration SO2. The modified ACF was characterized by iodine value and functional groups. The adsorption properties of low concentration SO2 on ACF-Mn-Cu50 were also studied. The result showed that the adsorption properties were improved with the granular Cu. Amount of Mn particles attached to the surface of ACF and the desulfurization rate of ACF-Mn-Cu50 both increased after second modification when the adsorption temperature was 60°C, the air velocity was Q1=0.3 L/min and Q2=0.4 L/min respectively and the concentration of SO2 was 0.62×10-4 μg/ml.