Objective:To contribute to the early diagnosis of Alzheimer disease (AD). Methods: we detected the visuospatial function in the patients with mild cognitive impairment (MCI) using the functional magnetic resonance imaging (fMRI). Nine patients with MCI and nine controls matching in age, gender, level of education and handedness distinguished the analogue clocks with the same location of the hands presented visually while the MR machine was scanning. The raw data of the fMRI were processed with the software AFNI. The reaction time and correct ratio were analyzed by means of independent-samples T test or paired-samples T test with the software Excel. Results:The patients manifested longer reaction time and lower correct ratio than the controls, the brain activation showed less intensity and extension in the patients bilateral parietal lobes,temporal neocortex adjacent to the occipital lobes and the extrastriatal visual cortex except for the right dorsal lateral prefrontal lobe. The activation was prominently in the right hemisphere. Conclusion: The patients with MCI have the deficit in visuospatial function, which can be tested by fMRI.