Objective To investigate whether childhood maltreatment（CM） can increase the risk of major depressive disorder（MDD） in adolescents and the regulatory role of gray matter volume（GMV） change in the association between CM and MDD in adolescents，and to identify possible neuroimaging indicators for MDD in adolescents to assist in early diagnosis. Methods A total of 47 adolescents with MDD，aged 12-17 years，who attended The First Affiliated Hospital of Chongqing Medical University from October 2021 to July 2022 were enrolled as MDD group，and 28 healthy controls，matched for age，sex，and years of education，were enrolled as control group. All subjects underwent three-dimensional T1-weighted magnetic resonance imaging（MRI） scans，and the voxel-based morphometry（VBM） methods were used to compare GMV between the two groups. The independent samples t-test was used for comparison between the two groups. The Spearman correlation analysis was used to investigate the correlation of GMV of different brain regions and 17-item Hamilton Depression Rating Scale（HAMD-17） score with Childhood Trauma Questionnaire-Short Form（CTQ-SF） score. A mediating effect model was established to investigate the regulating effect of GMV of different brain regions in the association between CM and depression，and the Bootstrap method was used for testing. The receiver operating characteristic（ROC） curve was used to investigate the value of GMV of different brain regions in the diagnosis of MDD. Results Compared with the control group，the MDD group had significantly higher total score of CTQ-SF and scores of each dimension（P<0.05）. Compared with the control group，the MDD group had significant reductions in the GMV of the left calcarine cortex （t=-5.61），the right middle temporal gyrus（t=-4.95），the left dorsolateral superior frontal gyrus（t=-4.59），and the right paracentral lobe（t=-4.27），with a P value of <0.05 based on voxel-based FDR correction and a voxel threshold of 1000. The reduction in the GMV of the left calcarine cortex had a certain accuracy in the diagnosis of MDD，with an area under the ROC curve of 0.843 and a Yoden index of 0.587. The GMV of the above four brain regions was negatively correlated with the total score of CTQ-SF，emotional abuse（EA） score，physical neglect（PN） score，and emotional neglect（EN） score（P<0.05），and the correlation between PN score and GMV of the left calcarine cortex was corrected by Bonferroni multiple comparisons（P<0.002）. The total score of CTQ-SF（r_s =0.611，P=0.000），EA score（r_s =0.617，P=0.000），EN score（r_s =0.604，P=0.000），and PN score（r_s =0.523，P=0.000） were significantly positively correlated with HAMD-17 score，which were all corrected by Bonferroni multiple comparisons（P<0.008）. The mediation analysis showed that GMV of the left calcarine cortex，the right middle temporal gyrus，the left dorsolateral superior frontal gyrus，and the right paracentral lobe showed an indirect effect on the association between CM and depression；GMV of the left calcarine cortex showed an indirect effect on the association between EN and depression；GMV of the left calcarine cortex and the right middle temporal gyrus showed an indirect effect on the association between PN and depression. Conclusion Adolescents with MDD suffer more from all dimensions of CM than healthy individuals. Reductions in GMV of the left calcarine cortex，the right middle temporal gyrus，the left dorsolateral superior frontal gyrus，and the right paracentral lobe play a crucial regulatory role in the association between CM experience and depression in adolescents，and different types of CM can affect the risk of depression through changes in GMV of different brain regions.