The antioxidant activity of capsaicin was evaluated through building antioxidant experiment model in vitro, taking capsaicin monomer as standard sample, and Vc as the contrast. By analyzing the reducing power of capsaicin and scavenging experiments on the DPPH radical, superoxide anion radical (O-2·), nitroso and hydroxyl radical (·OH), discussed capsaicin the antioxidant properties. The results showed that: reducing power of capsaicin increased with mass concentration increasing, and the DPPH radical, nitroso and clearance rate of ·OH with mass concentration increasing, and the scavenging effect and Vc basically similar, but with lower clearance to O-2·; the clearance of capsaicin to DPPH·, nitroso and IC₅₀ of ·OH were 0.02 mg/mL, 0.15 mg/mL, 0.28 mg/mL, respectively. The result suggested that capsaicin had good clearance on DPPH.