When blood pressure is measured, the right arm has a higher blood pressure value than the left arm, which may be due to physiological reasons such as different anatomical beginnings, or due to pathologic factors such as aortitis, aortic coarctation, and left subclavian artery stenosis. 1. Physiological reasons: when normal people use indirect manometry such as sphygmomanometer cuff pressure method for blood pressure measurement, there will be a difference of 5-10mmHg in the blood pressure of both upper limbs, which may be due to the different anatomical beginnings of the brachial arteries on both sides, and the right subclavian artery which sends out right brachial arteries originates from the trunk of the head and arm, with a larger blood runoff, resulting in a higher value of the right arm than the left arm blood pressure. 2. Pathological reasons: some diseases, such as multiple aortitis, congenital arterial malformation, aortic coarctation, left subclavian artery stenosis, etc., can lead to different degrees of aortic arch stenosis, resulting in abnormal distribution of blood pressure in the aortic arch, the blood pressure of the upper extremities of such diseases is often unequal, and more than 10mmHg. Blood pressure on both sides of the upper extremities is not equal, if within the normal range, it is physiological without worrying; if the blood pressure check is larger than the normal value, we should go to the hospital in a timely manner, so as not to delay the condition.