Abstract: In order to explore the optimum extraction process of polysaccharide and antioxidant activity in vitro in Peristrophe roxburghiana. In this study, Peristrophe roxburghiana was used as raw material to explore the effects of solid-liquid ratio, extraction temperature, time and frequency on the yield of polysaccharide. The extraction process of polysaccharide in Peristrophe roxburghiana was optimized by response surface methodology and the antioxidant activity of the polysaccharide was investigated by measuring its scavenging ability on DPPH·, ·OH, ABTS⁺· and other free radicals. The results showed that we could get the most quantity of polysaccharide extracted from Peristrophe roxburghiana, which reaches up to 11.05%, in these conditions: The solid-liquid ratio was 1:31 g/mL, the extraction temperature was 85 ℃, the extraction time was 118 min and the extraction frequency was 3 times. The scavenging ability of the polysaccharide against free radical was quantitatively related to the concentration of polysaccharide within a certain range. The IC₅₀ values of DPPH·, ·OH and ABTS⁺· radicals scavenged by the polysaccharide solution were 0.18, 0.73 and 0.64 mg/mL, respectively, indicating that the polysaccharide extracted from Peristrophe roxburghiana was with certain antioxidant activity. By exploring the optimal process and antioxidant activity of the polysaccharide extracted from Peristrophe roxburghiana, we provide a theoretical basis and reference for the further development and application of the polysaccharide in the future.