Abstract: Lignin was extracted from Acanthopanax senticosus remainders coming from pharmaceutical production process with acetone as extracting reagent. Lignin antioxidant capacity and yield were tested under singlefactor experiment,such as reaction temperature,reaction time,solidliquid ratio,acetic acid concentration,and solution concentration of acetone. The optimal conditions by a fourlevel orthogonal array design were as followings: reaction temperature 180 ℃, solution concentration of acetone 80%, solidliquid ratio 1∶20, and reaction time 80 min. The EC50 of the acetone organic lignin on DPPH was 1.518 mg/mL by verification experiments. The results indicate that the acetone organic lignin antioxidant capacity is better than that of Kraft lignin, but much lower than that of butylated hydroxyanisole (BHA).