Abstract: Objective To study the correlation between neurotransmitter activity and severity of depression in patients with depression.Methods Neurotransmitter level and total Hamilton rating scale for depression（HAMD） score in depression patients were detected with encephalofluctuography（EFG） analyzer and HAMD scale.Results The total HAMD score was≥20 in 39 depression patients and it was 20-35 in most patients（89.7%）.The GABA,glutamate,5-HT,noradrenaline（NE） and dopamine（DA） levels were obviously lower in depression patients than in controls（P＜0.05 or P＜0.01）,indicating that the total HAMD score is linearly related with 5-HT and NE levels（r=-0.932 for 5-HT,r=-0.930 for NE,P＜0.01）.Conclusion 5-HT and NE are closely related with the severity of depression.EFG can be used to measure the neurotransmitter level and can thus help to assess the severity of depression.