The extraction process conditions of total flavonoids from Flemingia macrophylla were optimized, and the extract's antioxidant properties were also studied. Firstly, the single factor test and response surface test were applied to optimize the alcohol reflux extraction process, and the antioxidant activity of the extract was finally evaluated. It was found that the best extraction time was 52 min, material-liquid ratio 1∶6 (g/mL), ethanol volume fraction 70%, extraction temperature 60 ℃. Rutin was used as the standard substance, the total flavonoid content of the extract is 75.47 μg/mg; the IC₅₀ of the extract for ABTS+· and DPPH· scavenging was 0.044 9, 0.212 3 mg/mL, respectively, and the IC₅₀ for the total antioxidant capacity and the reducing ability of Cu²⁺ and Fe³⁺ is 0.389 6, 0.221 9, 0.731 7 mg/mL. The best extraction process was established in this study, which could effectively obtain total flavonoids from Flemingia macrophylla; The total flavonoids extracted from Flemingia macrophylla showed intense in vitro antioxidant activity.