Postpartum depression refers to the special stage of depression that occurs within 4 weeks after delivery，which has a negative impact on the physical and mental health of the parturient as well as the intelligence，emotion and thinking of the baby.Due to the low attention to postpartum depression and the lack of effective medicines，the incidence and prevalence of postpartum depression are increasing year by year.In recent years，studies have found that the biological mechanism of postpartum depression is closely related to neurotransmitter disorders，neuroendocrine disorders and excessive release of inflammatory cytokines，and traditional Chinese medicine has definite curative effect in the treatment of postpartum depression，but the exact pathogenesis is not clear.Therefore，this paper summarized the research achievements of Chinese and foreign scholars on the biological mechanism of postpartum depression in recent years，to provide ideas for the clinical and basic research on postpartum depression with traditional Chinese medicine.