Major depressive disorder (MDD) is the most prevalent form of depression and is becoming a great challenge for public health and medical practice. Although first-line antidepressants offer therapeutic benefits, about 35% of depressed patients are not adequately treated, creating a substantial unmet medical need. A multicenter, double-blind, randomized, placebo-controlled phase 3 clinical trial was conducted in patients with MDD in China to assess the efficacy and safety of ansofaxine (LY03005), a potential triple reuptake inhibitor of serotonin, norepinephrine, and dopamine. Eligible 588 MDD patients were included and randomly assigned (1:1:1) to 8-week treatment with ansofaxine 80 mg/day(n= 187), ansofaxine 160 mg/day(n= 186), or placebo(n= 185). The primary efficacy endpoint was the Montgomery-Åsberg Depression Rating Scale (MADRS) total score change from baseline to the end of the study. Safety indexes included adverse events, vital signs, physical examination, laboratory tests, 12-lead electrocardiogram (ECG), and evaluation of suicide tendency and sexual function. Significant differences were found in mean changes in MADRS total score at week 8 in the two ansofaxine groups (80 mg, −20.0; 160 mg, −19.9) vs. placebo (−14.6;p< 0.0001). All doses of ansofaxine were generally well-tolerated. Treatment-emergent adverse events (TEAEs) were reported by 137 (74.46%) patients in ansofaxine 80 mg group, 144 (78.26%) patients in ansofaxine 160 mg and 125 (67.93%) patients in the placebo group. The incidence of treatment-related adverse events (TRAEs) was 59.2% (109 patients), 65.22% (120 patients) in the 80, 160 mg ansofaxine groups, and 45.11% (83 patients) in the placebo group. The initial results of this trial indicate that ansofaxine at both the 80 mg/day and 160 mg/day was effective and safe in adult patients with MDD. ClinicalTrials.gov Identifier: NCT04853407.