Depressive disorder has become one of the main causes of death and disability in the world， and its pathogenesis has not yet been determined. In recent years， more and more scholars believe that the occurrence of depression may be related to stress response. Stress response may cause changes in plasticity of nerve cells， abnormal regulation of hypothalamus pituitary adrenal axis and changes of neurotransmitter secretion， resulting in brain structure and function disorders， and eventually lead to the occurrence of depression.