This study developed a concentration-gradient extraction method (CGEM) for the Chinese herbal complex Si-Wu, and compared with the extraction efficiency of CGEM with that of the conventional extraction method (CEM). Instead of 70% ethanol solution used as the extractant in CEM, the concentration of ethanol solution in CGEM was increased from 0% to 70% during the extraction period. The results showed that the extraction efficiencies of CGEM for paeoniflorin, ferulic acid and catalpol increased by 21.6%, 44% and 96.6%, respectively, as compared with those of CEM in the same operation parameters without any additional cost. Meanwhile, the content of total phenolic compounds (TPC) and the trolox equivalent antioxidant capacity (TEAC) of extracts from Si-Wu with CGEM also increased. The potential of applying CGEM in pilot-plant scale was also demonstrated in this study.