Objective:To explore the characteristics of event-related potential of MDD(major depressive disorder) patients with suici-dal ideation. Methods:We collected MDD patients with suicidal ideation by certain inclusive and exclusive criterias in Mental Health Center,the First Affiliated Hospital of Chongqing Medical University,and recorded the event-related potent(ERP) of 20 non-treatment MDD patients with suicidal ideation when executing emotional stroop mission. Results:The total average reaction time of MDD patients with suicidal ideation was (695.04±2.16) ms;the reaction time was statistical significant between the different word-facial tasks(P<0.05);there is no statistical significance in the latentperiodofERP related components:P1,N1,P2,P3 of MDD patients with suicidal ideation under four words-facial interference.There were statistical significancesin the amplitude of ERP related components:N1,P2,P3,which under four words-facial interference. Conclusion:Attentional bias and cognitive function differences existed in different emotional-facial stimulus for MDD patients with suici-dal ideation.