Aim To study the effect of Echinacoside on immune function and the hepatocyte mitochondrial DNA relative content of experimentally aging model mice. Methods Mice were given sc 10%D-galactose 10 ml·kg-1,once daily for 8 weeks to establish the model of aging mice. Vitamin E group ,and ECH groups were given ig Vitamin E 40 mg·kg-1 and ECH 20,40,60 mg·kg-1,respectively at one time. The interleukin-2(IL-2) and interleukin-6(IL-6) content in peripheral blood was measured by ELISA method.Phagocytosis of peritoneal macrophages was tested by neutral red test. Proliferation and transformation of spleen lymphocytes induced by ConA were determined by MTT method. The mitochondrial DNA relative content of liver cells was measured by the means of SDS alkali decomposition from liver.Results The IL-2 content,phagocytosis of peritoneal macrophages and proliferation of spleen lymphocytes were obviously decreased in the aging model group as compared with those in the normal control group.The IL-6 content and mitochondrial DNA relative content of liver cells were significantly increased. ECH 20,40,60 mg·kg-1 and Vitamin E 40 mg·kg-1 could improve the IL-2 content,phagocytosis of peritoneal macrophages and transformation of spleen lymphocytes,and reduce the IL-6 content and mitochondrial DNA relative content of liver cells. Conclusion ECH can enhance immune function and reduce the mitochondrial DNA relative content of liver cells,which may be one of the mechanisms of anti-aging.