Abstract: ACP1 was extracted by water extraction and alcohol precipitation, then purified by DEAE- 52 and Sephdex G-100 column chromatography from fruiting bodies of Albatrellus caeruleoporus.The antioxidant activities of ACP1 were investigated by reducing power, DPPH, hydroxyl, superoxide anion radical scavenging, and chelating ability assays. The results showed that ACP1 had in vitro strong antioxidant activities, whose activities were positively correlated with concentration. The IC50 of reducing power, scavenging DPPH radical, hydroxyl radical, superoxide anion and chelating ability were 0.09, 0.27, 0.64, 0.42 and 0.62 mg / m L.It indicated that the ACP1 may be used as natural antioxidant additive in foods and medicines.