Abstract: In order to understand the effect of deep eutectic solvents (DESs) extraction conditions on the properties changes and antioxidant activity in vitro of Polygonatum sibiricum polysaccharides (PSP), Polygonatum sibiricum was taken as the main raw material, and the relative molecular weight, monosaccharide composition and antioxidant activities of polysaccharides extracted with DESs were analyzed. The results showed that compared with the traditional water extraction method, the yield of polysaccharides extracted by 70 ℃ DESs was 18%, which was 36% higher than that by traditional water extraction. The molecular weight of PSP decreased and the galactose content increased; the molecular weight of HDPSP which extracted at 100 ℃ was lower, and the main component was glucose. The scavenging rates of hydroxyl free radical and DPPH free radical and the total antioxidant capacity of Polygonatum sibiricum polysaccharide showed that the antioxidant capacity of Polygonatum sibiricum polysaccharide extracted with DESs at 70 ℃ was significantly higher than that of polysaccharide extracted at 100 ℃ and water extraction. When the concentration was 3.0 mg/mL, the total antioxidant capacity of polysaccharides extracted at 70 ℃ was 4.5 U/mL, 4.3 times that of water-extracted polysaccharides, and 7.4 times that of polysaccharides extracted at 100 ℃. Deep eutectic solvent can reduce molecular weight and improve antioxidant activity of Polygonatum sibiricum polysaccharide. The results can provide reference for the application of deep eutectic solvent in polysaccharide extraction.