Abstract: OBJECTIVE To observe the effect of Alligator Alternanthera extract on mice with chemical liver lesion. METHOD Chemical liver lesion models were made and ALT,AST,MDA and SOD activity determined. RESULT Serum ALT and AST levels of the mouse models were markedly higher than those in the control group(P<0.01),SOD activity was lower than that in the control group(P<0.01) and MDA content was higher than that in the control group(P<0.01),indicating successful model creation.Serum ALT and AST activity in high and medium dosage groups decreased markedly(P<0.01),MDA content dropped markedly and SOD activity increased greatly(P<0.01).Pathohistological observation indicated that liver lesion was markedly alleviated.CONCLUSION Alligator Alternanthera has protecting effect on chemical liver lesion.