Large and small doses of drugs for improving blood circulation and removing blood stasis were used in model rats to treat mild chronic hepatic damage induced by carbon tetrachloride (CCl4). The results show that large dose of Dang Gui (当归 Radix Angelicae Sinensis) and Dan Shen (丹参 Radix Salviae Miltiorrhizae) (drugs for regulating blood flow) and small dose of Yu Jin (郁金 Radix Curcumae) and Niu Xi (牛膝 Radix Achyranthis Bidentatae) (drugs for activating blood flow) can significantly elevate the activity of SOD (P<0.05) and/or lower the T/K ratio, markedly reduce the MDA content (P<0.05 or P<0.01) and significantly decrease the activities of ALT and AST (P<0.05 or P<0.01), demonstrating that these drugs are effective in combating oxygen free radicals (OFR) in chronic liver damage. On the contrary, large dose of Tu Bie Chong (土鳖虫 Eupolyphaga seu Steleophaga) and E Zhu (莪术 Rhizoma Curcumae) (drugs for removing blood stasis) tend to increase the ALT and AST (P<0.05) activities. The results suggest that the synergism of elevation of the SOD activity and reduction of T/K ratio contributes to the action of drugs for improving blood circulation and removing blood stasis in combating the liver damage induced by CCl4.