Abstract: OBJECTIVE To investigate TCM syndromes on maternal separation in C57/BL6 mice. METHODS Neonatal mice were intervened through maternal separation. The effects of maternal separation on spontaneous activities of mice were evaluated by field test and the effects on immobility times of mice were evaluated by forced swimming test and tail suspension test. Four diagnostic quantitative indicators measurement and quantitative dialectical method were employed to explore the state of Qi， Blood， Yin and Yang in mice. Hypothalamus-pituitary-adrenal (HPA) cortical axis function was observed through adrenocorticotropic hormone (ACTH) and corticosterone (CORT) determination. The level of energy metabolism was investigated through the measurement of cyclic adenosine monophosphate/cyclic guanosine monophosphate (cAMP/cGMP)， ATPase and superoxide dismutase(SOD). RESULTS No statistical significance (P>0.05) was observed in the total path of animal activities between each group in field test. Compared with the control group and MS15 group， in the forced swimming test and tail suspension test， the immobility time of mice of MS18 group was significantly increased (P<0.01). The levels of Yang heat， cAMP/cGMP， Na⁺-K⁺-ATPase and SOD significantly decreased (P<0.01)， while ACTH and CORT significantly increased (P<0.01) of MS18 group， compared to the control group and MS15 group. CONCLUSION Maternal separation shows significant effects on behavior in mice. The mice exhibit depression-like behavior， upset HPA axis balance and reduce body energy metabolism， which characterized as Yang deficiency symptoms in TCM.