TCD Doppler belongs to the category of ultrasonography, also known as transcranial Doppler ultrasound diagnostic technique. This technique is a more effective method of detecting cerebrovascular disease using color Doppler ultrasound diagnostic technology. This method uses the weak part of the head to establish a physiological transillumination window to perform a non-invasive examination of cerebrovascular disease in some of the large and small intracranial arteries. Through the color Doppler effect, the Doppler signal of blood flow in some intracranial arteries is detected comprehensively to reflect the basic condition of cerebrovascular disease. Although TCD can reflect the functional state and diseases of cerebrovascular relatively sensitively, it cannot completely display the intracranial vascular alignment.