Objective To investigate the diagnostic value of magnetic resonance imaging (MRI) on functional changes in patients with vascular cognitive impairment (VCI). Methods 98 VCI patients treated in our hospital were selected as the research group, while another 98 healthy people examined in our hospital were selected as the control group. All the VCI patients were evaluated by the cognitive function scale, and the results of MRI examinations were compared between groups. Results The scores of CCSE and MMSE in patients with dementia VCI were higher than those in nondementia VCI patients, the atrophy degrees of occipital, parietal, frontal and temporal lobes in patients with dementia VCI were greater than those in non-dementia VCI patients, and their differences were statistically significant (P<0.05). The atrophy degrees of occipital, parietal, frontal and temporal lobes in the research group were greater than those in the control group, and their differences were statistically significant (P<0.05). Conclusion MRI can reflect the functional changes of patients with vascular cognitive impairment. Therefore, MRI combined with cognitive function scale can be used in the diagnosis of VCI, so as to improve the accuracy of diagnosis.