Abstract: Objective To explore the effects of neuroplasticity on major depression disorder (MDD) with event related potentials (ERPs) of mismatch negativity (MMN) and sensory gating potentials P₅₀ for repetitive transcranial magnetic stimulation (rTMS) combined with antidepressant treatments. Methods A total of 159 patients with MDD randomly divided into two groups:75 patients in group A was administrated rTMS treatment for 2 weeks (15 days), and continues to give antidepressant of selective serotonin reuptake inhibitor (SSRI) regularly. 84 patients in group B was consistently administered the similar antidepressant. The 24-item Hamilton Depression Scale (HAMD-24), MMN latency, S₁-P₅₀ amplitude, S₂-P₅₀ amplitude and S₂-P₅₀/S₁-P₅₀ amplitude ratio, and the percentages of abnormal P₅₀ (S₂-P₅₀/S₁-P₅₀ ≥ 0.5) were assessed and measured before treatment, at the 2nd and the 10th weekend after treatment in two treatment groups. Meanwhile, 90 normal control cases was set up as control group (group C). Results At 2th and 10th week after treatment, the HAMD-24 scores were reduced remarkably than those before treatment in group A and B (P<0.001), and the scores in group A was lower than that in group B (P<0.001). MMN latencies and S₂-P₅₀ amplitudes after treatment in group A were significant shorter and lower than those before treatment in group A and after treatment in group B (P<0.05) (except for intergroup comparison of S₂-P₅₀ amplitude after treatment 10 weeks). No significant difference was found in S₂-P₅₀/S₁-P₅₀ ratio (except for after treatment 2 weeks) and percentage of abnormal P₅₀ between group A after treatment and group C (P>0.05). There were no statistical significance difference of ERPs between after treatment 2 weeks and 10 weeks in group A (P>0.05). No statistical differences of ERPs between before and after treatment in group B (P>0.05) was observed. Conclusion rTMS combined with antidepressant therapy was superior to single antidepressant treatment, and marked improved automatic processing and sensory gating of the brain senior functional electricalphysiological index. rTMS might induce effects of long-term potentiation/long-term depression like plasticity on brain, and keep brain function in a dynamic stability and balance. MMN and P₅₀ maybe become neuroplasticity index reflecting relevant the brain senior function.