Abstract:To evaluate the quality of Cardamine tangutorum O.E.Schulz and develop products，this study optimized the extraction process of polysaccharides from different parts of the plant and compared in vitro antioxidant activities of the polysaccharides. The extraction process of polysaccharides from Cardamine tangutorum O.E.Schulz was optimized by Box-Behnken experimental design.The polysaccharide content was measured by ultraviolet（UV）-visible spectrophotometry. The antioxidant properties of the polysaccharides were measured by assessing the scavenging capacity of hydroxyl radicals，1，1-diphenyl-2-picrylhydrazyl（DPPH）radicals，and 2，2'-azino-bis（3-ethylbenzothiazoline-6-sulfonic）acid（ABTS）cationic radicals of the polysaccharides and the total reducing power. The results showed that the optimal extraction process for polysaccharides from the aerial parts of Cardamine tangutorum O.E.Schulz was as follows：a material-liquid ratio of 1∶70（g/mL），extraction time of 200 min，and extraction temperature at 100 ℃，yielding an extraction rate of up to 11.67%.For the subterranean parts，the optimal extraction process was a material-liquid ratio of 1∶70（g/mL），extraction time of 180 min，and extraction temperature at 100 ℃，yielding an extraction rate of up to 18.71%.The results of the antioxidant assay showed that the half inhibitory concentrations（IC50）of hydroxyl radicals，DPPH radicals，and ABTS+ radicals of polysaccharides from the aerial parts of Cardamine tangutorum O. E. Schulz were 2.15，0.49 mg/mL，and 1.47 mg/mL，respectively，and the IC50 values of hydroxyl radicals and ABTS+radicals of polysaccharides from the subterranean parts were 3.47 mg/mL and 2.68 mg/mL，respectively. Polysaccharides from different parts showed lower reducing power.In conclusion，the polysaccharides from Cardamine tangutorum O. E. Schulz exhibited significant antioxidant activities，with those extracted from the aerial parts demonstrating stronger antioxidant capacity compared to those from the subterranean parts.