Low-level light therapy, which is a red or near-infrared light-employed therapeutic methodology, can act to help the brain repair in cases of traumatic brain injury and stroke. In this paper, we investigate the effects of near-infrared light therapy (NILT) for the recovery of blood flow of mice with cerebral hypoperfusion, which is a key mechanism leading to vascular dementia, induced by bilateral common carotid artery stenosis (BCAS). The mice are divided into three groups of 4-5 mice per group: a normal group (without BCAS operation), a BCAS group (without NILT), or a BCAS/NILT group. The LED with a peak wavelength of 810 nm and a power of 20 mW is arranged to illuminate on the top of the mouse head. The mice receive treatment from the LED source 3 times per week for one month. After the treatment, positron emission tomography is used to quantify the effects of NILT on whole brain and regional cerebral blood flow in the cortex, striatum, and hippocampus.