Abstract: With the extraction rate of polysaccharide as the index, on the basis of single factor experiment, Box−Behnken response surface methodology was used to optimize the extraction conditions of polysaccharides from Polygonatum kingianum. The polysaccharides were purified by DEAE cellulose ion exchange resin. The antioxidant activity of polysaccharides before and after purification was determined by ABTS+· clearance in vitro model. The results showed that the optimum technological conditions were as follows: solid-liquid ratio: 1∶30(g/mL), extraction time: 1.5 h, extraction temperature: 80 ℃. Under these conditions, the extraction rate of PKP was 20.70%. The SC₅₀ of crude polysaccharides, purified neutral polysaccharides and acid polysaccharides were 2.442, 0.825 and 0.444 mg/mL, respectively, which showed a dose-effect relationship with sample concentration, and the ABTS⁺· clearance was increased by 5.55 times after purification.