Abstract:This study used a composite tea prepared from Codonopsis pilosula and Astragalus membranaceus as materials to investigate the changes in total phenolic content，total flavonoid content，total antioxidant capacity，2，2′-azino-bis-（3-ethylbenzothiazoline-6-sulfonic acid） （ABTS） cation radical scavenging rate，1，1-diphenyl-2-picrylhydrazyl （DPPH） radical scavenging rate，and hydroxyl radical scavenging rate of the tea infusion under different brewing conditions. Response surface methodology was further used to optimize the brewing conditions of the C. pilosula and A. membranaceus composite tea. The results showed that the total phenolic content，total flavonoid content，total antioxidant capacity，ABTS+ radical scavenging rate，DPPH radical scavenging rate，and hydroxyl radical scavenging rate of the tea infusion decreased with the increase in brewing water volume. When the brewing water volume was 100 mL，all antioxidant indicators reached their peak values. The total antioxidant capacity of the tea infusion was the highest when the brewing time was 25 min and the brewing temperature was 90 ℃. The optimal brewing conditions obtained by response surface methodology were a brewing water volume of 100 mL，a brewing time of 26.2 min，and a brewing temperature of 90 ℃. Under these conditions，the total antioxidant capacity of the composite tea infusion was 1.638 μmol/mL，which was close to the predicted value of 1.645 μmol/mL，confirming the feasibility of the model.