Doppler is able to examine the lack of blood supply to the brain. Doppler is mainly used to examine the general condition of intracranial blood vessels through the skull using color ultrasound, mainly the vessels that make up the Willis ring of intracranial blood vessels. Generally, intracranial blood vessels are divided into anterior and posterior circulation, and the anterior circulation mainly includes the middle of the brain, the front of the brain and the anterior traffic, etc. After Doppler examination, it is possible to find out the blood vessels, whether there is stenosis and how much blood flow rate. If the degree of stenosis is severe, the patient’s blood flow rate can be found to be severely increased. If the patient’s blood flow velocity is slowed down and the vascular elasticity is poor, chronic cerebral insufficiency is considered, and symptomatic treatment is recommended to improve circulation and activate blood circulation. Brain Doppler can also check the posterior circulation of Willis ring, which mainly refers to the blood flow velocity of both vertebral and basilar arteries and posterior cerebral arteries, as well as the degree of stenosis of the blood vessels, and in severe cases, it can also find out whether there is blood theft in the blood vessels and other phenomena, and give appropriate treatment according to the patient’s vascular condition.