Abstract: Objective To study the conditions of ¹¹C-PIB PET dynamic imaging for intra-cranial senile plaques and the features of ¹¹C-PIB PET imaging for healthy aged control subjects（HC） and Alzheimer disease（AD） patients. Methods 6 AD patients and 7 health control（HC） subjects were enrolled in this study.Sequential ¹¹C-PIB PET imaging was performed for each subject.Features of the images obtained were analyzed by 2 physicians of nuclear medicine.The region of interest（ROI） was used to plot the cerebral cortex and infra-cortical nuclear diagram to calculate and analyze the SUN values for each brain region at different time points. Results ¹¹C-PIB could rapidly pass through the blood-brain barrier and was then quickly cleared from healthy brain tissues.The time-radioactivity curve showed that the radioactivity was cleared at a lower speed in AD patients than in HC.The difference in ratio of brain region/cerebellum（except for pons /cerebellum and protein /other brain regions and cerebellum out of the cerebellum） between AD patients and HC was statistically significant（t=4.06-7.28,P＜0.05）. Conclusion ¹¹C-PIB PET imaging is an effective tool for the diagnosis of AD.