In this paper, the extraction process of flavonoids from Ligusticum was optimized by single factor test and response surface methodology, and the antioxidant experiment in vitro was carried out. The optimum extraction conditions were as follows: extraction time 2.5 h, extraction temperature 83 ℃, ethanol concentration 84%, liquid?solid ratio 35 L/g (the ratio of ethanol volume to Ligusticum jeholense powder sample mass). Under these conditions, the yield of flavonoids from Ligusticum was （22.64±0.18） mg/g. The results of antioxidant experiment in vitro showed that flavonoids from Ligusticum had certain antioxidant capacity. The clearing effect of ·DPPH is the best, the clearing effect of ·OH is the second, and the clearing effect of·O^2- is the worst. It also has the ability to restore Fe³⁺.