Objective: To study the extraction and antioxidant capacity of cohosh polysaccharides in vitro. Method: Polysaccharides were extracted from cohosh by water extraction and alcohol precipitation. The total antioxidant capacity of cohosh polysaccharides was determined by ABTS method. The DPPH?scavenging capacity of cohosh polysaccharides was studied by colorimetry. Result: When the concentration of cohosh polysaccharides was 1.6 mg/mL, its total antioxidant capacity reached 0.64 mmol/L and the scavenging rate of DPPH?reached 67.94%. Conclusion: Cohosh polysaccharides has good antioxidant capacity in vitro and is expected to be developed as a natural antioxidant.