【Objective】To compare the volumes of brain regions and the white matter hyperintensities（WMH）in Alzheimer′ s disease （AD）and  vascular dementia（VaD）patients，and discuss values of magnetic resonance imaging（MRI）in the differential diagnosis of AD and VaD.【Methods】The clinical data and MRI images of 35 patients with VaD and 74 patients with AD were retrospectively analyzed. Volumes of different brain regions and WMH were measured by using AccuBrainTM system and visual rating scale was used to assess WMH. We then compared the volumes of brain regions and the WMH between AD and VaD. The principal component analysis（PCA）and logistic regression analysis were adopted for differential diagnosis. Receiver operating characteristic（ROC）analysis was performed to evaluate the diagnostic efficiency of the indexes.【Results】①Compared with VaD patients，AD patients showed statistically smaller volumes of total intracranial volume，brain parenchyma，gray matter，white matter，hippocampus，amygdala，hypothalamus， frontal lobe（left，right），occipital lobe（left，right），temporal lobe（left，right），parietal lobe（left，right），hippocampus（left，right），amygdala（left，right），hypothalamus（left，right）（P<0.05）. ②There was statistically significant difference in the visual scores for deep WMH（DWMH）between AD and VaD patients（P=0.015）. The absolute and relative volumes of WMH in VaDpatients were statistically larger than those in AD patients（P<0.05）. ③PCA revealed eight important parameters including brain parenchyma ，hippocampus ，amygdala ，hypothalamus ，frontal lobe（left），occipital lobe（left），temporal lobe（left）and parietal lobe（left）.The identification model consisting of amygdala，occipital lobe（left）and absolute volume of WMH was established based on logistic regression analysis. ④Among all the indexes，the identification model had the best diagnostic performance to differentiate AD from VaD and its sensitivity and specificity were 81.1% and 74.3% ，respectively.【Conclusions】There are significant differences in both volumes of certain brain regions and severity of WMH between VaD and AD patients. The cranial MRI is of great value for the differential diagnosis of VaD and AD.