Objective:To investigate the underlying neuroimaging mechanism of migraine without aura (MwoA) by using methods of voxel-based morphometry (VBM) and resting-state functional connectivity (FC).Methods:Twenty-five MwoA patients admitted to Department of Neurology, the Second Affiliated Hospital of Xuzhou Medical University from September 2020 to June 2023 were recruited as MwoA group, and 22 volunteers were recruited as healthy control (HC) group. Demographic, clinical characteristics, scores of Hamilton Anxiety Scale (HAMA), Hamilton Depression Rating Scale (HAMD) and Montreal Cognitive Assessment (MoCA) of all subjects were collected; MwoA patients also received Migraine Disability Assessment Questionnaire, Headache Impact Test-6 and headache Visual Analogue Scale assessments. All subjects underwent high-resolution 3D-T 1 and resting-state functional magnetic resonance imaging scanning. The SPM12 software was used to compare the difference in gray matter volume (GMV) between the 2 groups by VBM method. The GRETNA software was adopted to calculate the whole brain FC with anatomical automatic labeling 90 as the regions of interest, and the difference in FC between the 2 groups was statistically analyzed by two-sample t-test. Pearson partial correlation was used to analyze the correlation between brain GMV and FC changes and clinical features and scale scores of MwoA patients. Results:There existed no statistically significant difference between the 2 groups in age, gender, education, scores of HAMA, HAMD and MoCA (all P>0.05). Migraine Disability Assessment Questionnaire, Headache Impact Test-6 and headache Visua Analogue Scale scores of MwoA patients were (8.86±4.55), (50.27±6.35) and (6.68±1.73). Compared with the HC group, GMV was significantly decreased in the right superior frontal gyrus (SFG), right cingulate gyrus (CG) and left thalamus in the MwoA group ( P<0.05, false discovery rate corrected). In addition, the MwoA group showed decreased FC between left thalamus and right cuneus, left lingual gyrus (LG) and bilateral precuneus; decreased FC between right thalamus and right cuneus, right LG and right precuneus; decreased FC between right cuneus and left precuneus and right SFG; decreased FC between left LG and bilateral precuneus, decreased FC between right LG and right precuneus and left SFG; decreased FC between left precuneus and bilateral SFG, and between right precuneus and right SFG (edge P<0.001, component P<0.05, network-based statistics correction, interation=2 000). In MwoA patients, the FC (z-value) between left thalamus and right cuneus was negatively correlated with the duration of disease ( r=-0.530, P=0.011). Conclusions:MwoA patients showed decreased GMV in right SFG, CG and left thalamus. In MwoA patients, FC between thalamus and visual network (VN) and default mode network (DMN) was significantly decreased, and FC among VN, DMN and executive control network was significantly decreased. These changes in brain structure and function may be an adaptive change in the central sensitivity and responsiveness to pain stimuli, and may be an important neuroimaging mechanism of MwoA.