The study aims to evaluate the efficacy and safety of GW117 Tablets compared to placebo in adults participants with MDD over a period of 8 weeks.

Inclusion Criteria:

• Outpatients aged 18 to 65 years (including both limits), either male or female;
• Meet the diagnostic criteria for depression in DSM-5 (the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders), without psychotic symptoms;
• Have a total score of ≥ 22 on the 17-item Hamilton Depression Rating Scale (HAM-D17) at both screening and baseline visits;
• Have a Clinical Global Impression - Severity (CGI-S) score of ≥ 4 at both screening and baseline visits;
• Voluntarily participate in this trial and sign the informed consent form, and be able to comply with the planned visits, treatment plan, laboratory tests and other research procedures.

Exclusion Criteria:

• Allergic constitution (such as those allergic to two or more drugs or foods) or known to be allergic to similar products like agomelatine;
• Have previously received adequate and full-course treatment with agomelatine but showed no effect, or treatment-resistant depression (those who have used at least two antidepressants in adequate and full-course treatment but still showed no effect);
• HAM-D17 scale score reduction rate is ≥25% compared to the baseline period;
• High suicide risk; history of suicide attempts within one year before screening; suicidal or self-harming behavior during the screening period; score of ≥3 on item 3 (suicide item) of the HAM-D17 scale;
• Diagnosed with any disease other than depression according to DSM-5, including anxiety disorders, neurodevelopmental disorders, schizophrenia spectrum and other psychotic disorders, bipolar and related disorders, obsessive-compulsive and related disorders, trauma and stress-related disorders, dissociative disorders, anorexia or bulimia nervosa, personality disorders, etc.;
• Depression secondary to other mental or physical diseases. Note: Other inclusion/exclusion criteria may apply