Objective To explore the pathological mechanism of brain function and structure in young patients with major depressive disorder by diffusion tensor imaging(DTI)and resting state functional magnetic resonance imaging(fMRI).Methods Sixteen participants diagnosed with major depression (MD) and 16 healthy age and gender-matched controls(HC) were recruited. Resting state fMRI and DTI brain scans were performed on all participants. A voxel-based method (VBM) was used to analyze the DTI datasets, and regional homogeneity (ReHo) approach was applied to preprocess the fMRI datasets. The value of fractional anisotropy (FA) and ReHo maps were obtained in the whole brain.Results FA values in the MD group were significantly lower than those of the healthy controls in the white matter of the left middle temporal gyrus, right middle frontal gyrus, left medial frontal gyrus, right precentral gyrus, left angular gyrus, left fusiform gyrus, left superior temporal gyrus, right middle temporal gyrus, right sub-gyral, left insula, and left pyramis (P＜0.01). ReHo in the MD group decreased in the left superior frontal gyrus, right superior frontal gyrus, left middle frontal gyrus, right middle frontal gyrus, left medial frontal gyrus, right medial frontal gyrus, left paracentral lobule, right paracentral lobule, right inferior parietal lobule, left postcentral gyrus, right postcentral gyrus, left middle occipital gyrus, left lingual gyrus, right putamen, right cingulate gyrus, right cuneus, left superior temporal gyrus, and right middle temporal gyrus (P＜0.01). Conclusion Abnormality of brain white microstructure and function exist widely in young patients with major depressive disorder. Abnormal connection of structures and function between the brain areas may be the key reason for the depression.