Inclusion Criteria:  1.a Man or a woman with major depressive disorder(MDD) as the primary diagnosis according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria (classification code 296.22、296.23、296.32、296.33) 2.Has a Montgomery Åsberg Depression Rating Scale (MADRS) total score of 26 or greater at Screening and Baseline Visits. 3.Has a Clinical Global Impression - Severity of Illness (CGI-S) score of 4 or greater at Screening and Baseline Visits.  Exclusion Criteria:  1.has major depressive disorder with psychotic features according to the DSM-5. 2.Current or history of: bipolar disorder、schizophrenia、anixety disorder、insomnia、any substance abuse or dependence and other psychiatry disorder as defined in the DSM-5. 3.Current or history of a clinically significant neurological disorder (including epilepsy、Alzheimer disease, Parkinson disease, multiple sclerosis, Huntington disease). 4. has Serious body disease such as neurological disorders、cardiacvascular disorders、hepatic disorders、 renal disorders, blood system disorders and endocrine disorders. 5. Current or history of cancer( except basal cell of the skin and preinvasive carcinoma of cervix uteri). 6. Current or history of angle-closure glaucoma. 7. has made a suicide behavior in the previous 1 year ，or has a score greater than or equal to 4 on item 10 (suicidal thoughts) of MADRS . 8.has taken fluoxetine within 4 weeks prior to initial dosing. 9. has taken other antidepressive medications or antipsychotic medications within 2 weeks prior to initial dosing. 10.has psychotherap at Screening and/or Baseline Visits. 11.has had physiotherapy within 3 months prior to initial dosing. 12.Has an alanine aminotransferase, aspartate aminotransferase or total bilirubin level greater than 1.5 times the upper limits of normal. 13.Has an alanine aminotransferase, aspartate aminotransferase level greater than 2 times the upper limits of normal；or total bilirubin， direct bilirubin，creatinine level greater than 1.5 times the upper limits of normal；or a thyroid stimulating hormone value outside the normal range. 14.Has an abnormal electrocardiogram confirmed as clinically significant by the investigator. 15.Has a history of severe allergies.