Lignin was extracted from the Acanthopanax senticosus remainders, coming from pharmaceutical production process, with high boiling solvent (HBS) (1,4-butanediol) as the extracting reagent. We discussed the effects of reaction temperature, reaction time, solid-liquid ratio, acetic acid concentration and solution concentration of 1,4-butanediol on lignin yield and antioxidant capacity, and determined the optimal process. The results showed that there were significant differences on lignin antioxidant capacity among these factors. The reaction temperature is the most significant factor and the reaction time is the second factor among these factors. At the same lignin solution concentration, the antioxidant capacity of the lignin extracted with HBS is better than that of Kraft lignin, but much lower than that of butylated hydroxyanisole (BHA).