Inclusion Criteria:  Meets the Diagnostic and Statistical Manual of Mental Disorder, Fourth Edition Text Revision (DSM-IV-TR) criteria for Major Depressive Disorder (MDD): a single or recurrent episode without psychotic features. Codes are as follows: F32.0, F32.1, F32.2, F33.0, F33.1, F33.2. Outpatients. Male or female subjects aged 18-65 years. HAMD-17 score of the baseline period and screening period is 18-24. Women of childbearing potential must be willing to use acceptable methods of contraception throughout the study period and the following one month. The patient fully understands and signs the informed consent form.  Exclusion Criteria:  Patient has survived a suicide attempt or has acute suicidal tendencies (HAMD-17 Item3 ≥3). Comorbidity according to DSM-IV-TR, axis-I except for major depressive disorder. HAMD-17 reduction ratio ≥25% within one week from the screening to the baseline period. Depressive episode secondary to psychiatric illness or somatic disease. Serious and unstable diseases such as cerebrovascular disease; liver and kidney disease; disease of internal secretion (abnormal thyroid function); hemopathy; seizures, or other encephalopathies. History of alcohol or drug abuse over the last 6 months. Allergic history to Xiongdan Wan, or serious drug allergic history. Pregnant or lactating women and women of childbearing potential throughout the study period; men who have the desire of fertility within six months. Clinically significant changes in ECG or laboratory tests, including >1.5 times the upper limit of normal liver function; over the limit of normal renal function and blood sugar; abnormal cardiac troponins; obvious abnormity in the thyroid function. Treatment with modified electroconvulsive therapy (MECT) or repetitive transcranial magnetic stimulation (rTMS) in the past three months. Treatment with a systematic psychological treatment in the past three months.