Aim To evaluate the correlation of ambulatory arterial stiffness index(AASI) and carotid atherosclerosis in primary hypertension patients. Methods 124 primary hypertension patients and 70 healthy people were selected.The carotid artery intima-media thickness(IMT) were determined by ultrasonography.Primary hypertension patients were divided into two groups according to IMT: IMT≥0.9 mm as carotid atherosclerosis and IMT<0.9 mm as non carotid atherosclerosis.Twenty-four-hour ambulatory blood pressure monitoring(ABPM) was performed and the blood pressure parameters were analyzed to calculate AASI. Results IMT and plaque score in primary hypertension group was higher than that in healthy control group(1.178±0.214 mm and 0.806±0.356 vs 3.17±2.44 mm and 1.02±1.51,P><0.01).AASI in primary hypertension group was higher than that in healthy control group(0.56±0.14 and 0.41±0.12,P><0.01).And so was in carotid atherosclerosis group and non carotid atherosclerosis group(0.59±0.12 and 0.50 ±0.11,P><0.05).AASI were correlated with IMT positively(r=0.325,P><0.01). Conclusion AASI was closely related to carotid atherosclerosis in primary hypertension patients.