Magnetic resonance imaging has shown its important role in both early diagnosis of Alzheimer's disease and revealing the Alzheimer's disease pathogenesis. Structural magnetic resonance imaging include lineal mesure, volume measure and volume rendered. They can detect the abnormal brain structure, especially the change of mesial temporal lobe (hippocampus, amygdale) in early onset of Alzheimer's disease. Recent studies more focused on functional imaging which can find the functional changes in brain. Prior to structural changes, functional changes happen, so it can reflect the sutile pathological process in Alzheimer's disease. The functional imaging mainly refers to magnetic resonance spectroscopy, functional magnetic resonance imaging, diffusion weighted imaging and diffusion tensor imaging. As developing of these new technologies, we know more and more about pathogenesis and biological characteristics of Alzheimer's disease.