Objective To investigate changes of structures, expression of Bax protein activities of superoxide dismutase(SOD) and catalase(CAT), and contents of maleic dialdehyde(MDA) in the liver of filial mice and activity of glutamic-oxalacetic transaminease(GOT) and glutamic-pyruvic transaminase(GPT) in serum after injected ephedrine. Methods Totally 48 filial mice were used in this study. They were intraperitoneally injected with escalation doses (2.0g/L,3.0g/L and 4.0g/L ) ephedrine and the same amount of saline. Changes of the liver weight were examined. Activities of SOD, CAT, GOT, GPT as well as content of MDA were determined by colorimetry. Hepatic structures of 5, 10 and 15 days filial mice were observed by optical microscopy after injected ephedrine and the expression of Bax protein was measured by immunohistochemical staining. Results The liver weight of filial mice of the experimental groups was lower than the control groups at day 5 10 and 15 after injected ephedrine. The activity of SOD and CAT increased in the early ages and，then decreased with the extension of time and the increasing doses of the drug, SOD and CAT activities of the experimental groups were higher at day 5(EM>P/EM> <0.05） and lower at day 10(EM>P /EM><0.05） and day 15(EM>P/EM> <0.01） than that of the control group. While MDA content decreased firstly and then increased, MDA content of the experimental group lower than the control group at day 5 (EM>P/EM> <0.05), and higher than the control group at day 10 and 15(EM>P/EM> <0.01). The activity of GOT and GPT in filial mice serum of the experimental groups were higher than the control groups after injection of ephedrine(EM>P/EM> <0.05 orEM> P/EM> <0.01). Liver of filial mice appeared various degrees of damage after ephedrine injection, such as hepatic plate atrophy, hepatic sinusoid expand, the cell boundaries fuzzy and endotheliocyte fall off. The intensity of the expression of Bax protein of the experimental groups was higher than the control group after ephedrine injection(EM>P /EM><0.05 orEM> P/EM> <0.01). Conclusion The ephedrine affects the liver of developmental filial mice. This damage may be correlated with the lo