【】 Objective: To observe the blood flow in V2 segment of vertebral artery in patients with V1 segment occlusion using color Doppler ultrasound. Methods: 110 patients who were diagnosised V1 segment of vertebral artery occlusion by carotid ultrasound. To explore the blood flow signal,direction,speed and spectrum in V2 segment of vertebral artery. Results: In these patients, we can obtain 3 types of blood flow in V2 segment of vertebral artery. First, low speed and impulses forward flow; Second, systolic reversal flow; Third, bidirectional blood flow. Conclusion: It is more accurate to detect the blood flow in the in V2segment of vertebral artery in patients with initial segment occlusion by Color Doppler Ultrasonography.