Aim To probe the effect of blood pressure on hemodynamic indexes in cerebral vascular and carotid vascular by vascular ultrasound. Methods 225 patients with essential hypertension who accompanied with carotid artery atherosclerotic plaque,were divided into mild hypertension group (n=30),moderate hypertension group (n=61),and severe hypertension group (n=129),according to the controlled blood pressure. Meanwhile 94 patients with normal blood pressure who were not accompanied with hyperglycaemia,hyperlipemia and carotid artery atherosclerotic plaque,were chosen as the control group. The average blood flow rate (Vm) and pulsatility index (PI) of middle cerebral artery (MCA),anterior cerebral artery (ACA),postrior cerebral artery (PCA) and vertebral artety (VA) were detected by transcranial Doppler (TCD). The average blood flow rate and pulsatility index of common carotid artery,internal carotid artery and vertebral artery were detected by colour Doppler ultrasonography. Results (1) 24 h ambulatory blood pressure showed the blood pressure in hypertension groups were significantly increased compared with control group (P<0.05). (2) TCD showed the Vm and PI of cerebral artery in hypertension groups significantly differed from control group (P<0.05); and the Vm of cerebrovascular in hypertension groups was decreased with increasing the blood pressure,but PI was increased. (3)Colour Doppler ultrasonography showed the Vm and PI of carotid artery in hypertension groups significantly differed from control group (P<0.05); and the Vm of carotid artery in hypertension groups was decreased with increasing the blood pressure,but PI was increased. Conclusion The blood pressure affected the cerebral vascular and carotid vascular hemodynamic indexes. The trend of vascular hemodynamic indexes was getting severe as blood pressure elevated. In terms of cerebral and carotid vascular hemodynamic indexes,ideal blood pressure should be lower than 140/90 mmHg. The change of cerebral and carotid vascular can be objectively evaluated using TCD and colour Doppler ultrasonography. And we can provide the evidence for the clinical diagnose and cure.