Abstract: We extracted crude polysaccharide (BPS) from bamboo leaves by the method of supercritical CO2 extraction. The BPS was fractionated and precipitated by ethanol, and then protein was removed and further separated and purified by cellulose column. Physical and chemical indicators of the purified BPS were investigated. Results showed that: the crude polysaccharide extracted with supercritical CO2 technique was precipitated by ethanol at the volume concentration of 70%, obtaining a yield of pre-purified product 17.75%, the content of polysaccharide in it was 9.586 mg/g, and its total antioxidant capacity was 2.556 mg/g VC. Protein in the pre-purified product was removed by Sevag. Then neutral polysaccharide was obtained through DEAE-52 cellulose column, with an average molecular weight of 5.051×104. Its IC50 value was 0.178 mg/g BPS, showing a better DPPH scavenging ability than VC (IC50 value 0.158 mg/g).