Objective To explore the changes of brain functional imaging of hyperactivity of liver yang in spontaneously hypertensive rats (SHRs) by positron emission computed tomography (PET). Methods 8 SHRs were taken as model group and 10 normal SD rats as control group. The rats in the model group were administrated with Fuzi decoction for 28 d, then the brain functional imaging of 18F-FDG PET was carried out respectively, and the data of the two groups were tested with SPM2 image analysis software to obtain the areas of glucose metabolism in the brain of SHRs with hyperactivity of liver yang. Results Compared with control group, there were decreased glucose metabolism observed in right diencephalon, midbrain tectum, thalamus, basal nucleus, bilateral cerebral hemispheres, caudate nucleus, striatum, screen nucleus and caudate nucleus (P<0.05), while increased in left cerebral hemispheres, combined fibers and corpus callosum in model group(P<0.05). Conclusion PET can directly display the specific brain areas of the functional change of the spontaneous hypertension with hyperactivity of liver yang, which provides a reliable basis for early clinical diagnosis and prevention of cognitive dysfunction caused by hypertension.