Objective:To investigate the attention deployment emotion regulation disorder and its neural mechanisms in major depressive disorder(MDD).Methods:Twenty-six MDD patients(MDD group) and twenty-nine healthy control individuals(control group) were enrolled in this study.The accuracy and reaction time were recorded in the attention deployment behavioral paradigm.Neuroscan 64 Brain Evoked Potentiometer was used to detect the N1 and P3 components of the above two groups of subjects.SPSS 16.0 software were used to analyze the data.Results:(1)In the accuracy of attention deployment paradigm, the group main effect was significant ( F=11.626, P=0.001), indicating that the MDD group (0.82±0.01) was significantly lower than the control group(0.89±0.01)( P=0.001). In the reaction time of attention deployment paradigm, the group main effect was significant( F=16.55, P<0.01), indicating that the MDD group (1 460.82±41.86)ms)was significantly higher than the control group(1 226.31±39.63)ms)( P<0.01). (2)In the event-related potential of attention deployment paradigm, the group main effect of N1 was not significant ( F=2.949, P=0.092), and the interaction between task and group was significant ( F=4.756, P=0.034), indicating that the N1 amplitude induced by the MDD group in the calculation task(-3.699±0.441)μV) was significantly smaller than that of the control group (-5.055±0.418)μV)( P=0.030). The group main effect of P3 was not significant ( F=1.165, P=0.285), and the interaction between task and image attributes was significant ( F=11.602, P=0.001), indicating that the P3 amplitude induced by negative images(2.757±0.438)μV) was significantly higher than that of neutral images (1.963±0.460)μV)( P=0.002). Conclusion:Patients with MDD have difficulty transferring attention in emotional strategies, and it occurs in the early stages.