Objective To investigate the value of 3.0T high-resolution magnetic resonance imaging (HR MRI) in the diagnosis of middle cerebral artery stenosis in young and middle-aged patients. Methods Eighty-eight young and middle-aged patients with middle cerebral artery stenosis who were admitted to the hospital from January 2013 to December 2017 were enrolled in the study. Digital subtraction angiography (DSA) and 3.0T HR MRI were performed and the value of 3.0T HR MRI in the diagnosis of middle cerebral artery stenosis in young and middle-aged patients was analyzed. Results A total of 162 middle cerebral arteries were examined in 88 patients. Compared with results of DSA, the sensitivities of 3.0T HR MRI in the diagnosis of mild stenosis, moderate stenosis, severe stenosis and occlusion in young and middle-aged patients with middle cerebral artery stenosis were 90.70%, 90.30%, 84.62% and 100%, respectively. The specificities were 97.48%, 93.64%, 98.53% and 99.34%, respectively. The accuracy rates were 95.68%, 92.59%, 96.30% and 99.38%, respectively, and the diagnostic consistency was 0.888, 0.832, 0.858 and 0.949, respectively. 3.0T HR MRI showed that there were 87 stable plaques and 75 unstable plaques in 162 middle cerebral arteries. The fiber cap the stable plaque was intact, without lipid core or bleeding in plaques. Some unstable plaques showed lipid core and bleeding in plaques. Conclusion 3.0T HR MRI is of high reliability and validity in the diagnosis of young and middle-aged patients with middle cerebral artery stenosis, with good consistency with results of DSA. It can clearly show the middle cerebral artery plaques and is of positive value for the diagnosis of cerebral artery stenosis in young and middle-aged patients.