Objective To explore the influence of early emotional trauma on treatment effect of groupcognitive behavior therapy (GCBT) in mild depression patients. Methods Totals of 102 mild depression patients were recruited in this study. All patients received standardized GCBT. Early Trauma Inventory Self Report-Short Form (ETISR-SF) was used to investigate childhood maltreatment. Hamilton Depression Scale (HAMD-17) was used as primary outcome in baseline，at 4 weeks，8 weeks，12 weeks of treatment，as well as 24 weeks，36 weeks，48 weeks during follow up. Patients were divided into high emotional trauma group and lowemotional trauma group based on the median of emontional trauma. The treatment effects were compared between two groups. Results Patients in two groups all met clinical cure standard after 12 weeks’treatment and 48 weeks’follow up. Early emotional trauma showed significant interaction effect (F=3.72，P＜0.05) and no significant group effect (F=1.36，P=0.247). Simple effect analysis showed that both groups improved significantly after treatment (high emotional trauma group：F=77.98，P＜0.01；low emotional trauma group：F=22.45，P＜0.01). Although the improvement speed between two groups showed no significant difference (t=1.19，P=0.237)，depressive score oflow emotional trauma group decreased faster than that of high emontional trauma group significantly (t=-2.54，P=0.013). Conclusions Depression symptom would be significantly improved and lasting after GCBT in allmild depression patients regardless of the degree of emotional trauma. But at the beginning，patients with high emontional trauma improve slower.