Blood pressure is not measured in the hand, but in the upper arm. Clinical accuracy of blood pressure measurement is not based on left and right, but on physiological differences between the right and left hands, and clinical guidelines recommend measuring blood pressure in the right upper arm. Since the blood vessels of the right hand come from the branches of the head arm trunk, the blood pressure of the right upper arm is usually higher than that of the left upper arm, and it is generally 5 to 10 mmHg above the normal range, and if it exceeds this range, it indicates an abnormality, which is usually due to aortitis or congenital arterial anomalies. First time patients need to measure the right and left upper arm, observe and record the data, patients with suspected cardiovascular disease, and even first time patients need to measure the upper and lower extremity blood pressure changes, because the upper and lower extremity blood pressure changes are different, the difference between the upper and lower extremity blood pressure can be up to 20 to 40 mm Hg. If abnormal, it can be considered as the abdominal aortic stenosis, aortitis and so on. Measurement of blood pressure is not the hand, but the upper arm, because the blood pressure of the right upper arm is higher than that of the left upper arm, so the clinical guidelines recommend measuring the blood pressure of the right upper arm, if the patient has an abnormal blood pressure, it is recommended that the patient go to the Department of Cardiology to find out the cause of the problem in time, so as to avoid delaying the treatment.