Abstract: To achieve the reuse of the waste tea resources and explore the activity in vitro antioxidant activity of Xinyangmaojian tea dust polysaccharide, in this study, different concentration of final ethanol precipitation was used to optimize Xinyangmaojian tea polysaccharide extraction. Then the crude polysaccharides were separated and purified twice by DEAE-52 cellulose and Sephadex-100 dextran gel, and the pure polysaccharides, purity identification, determination of molecular weight, infrared spectroscopy and in vitro antioxidant activity were conducted. The results showed that the yield rate of 90% ethanol was the highest (2.47%). After two times of fractional purification, XPS-5B was obtained with the purity of 92.4%. XPS-5B conformed to the structural characteristics of polysaccharides from active plants, and glycosidic polysaccharide was of type β, with a molecular weight of 41208 Da. The antioxidant activity of XPS-5B increased gradually with the increasing of component concentration. When the concentration of XPS-5B was 1.20 mg/mL, the scavenging rate of DPPH free radical and hydroxyl free radical was 89.18% and 90.62%, respectively. The total reducing power absorbance value was 0.536, compared with the unpurified polysaccharides, XPS-5B had strong antioxidant activity.