High blood pressure in the right arm but not in the left arm may be simple hypertension or hypertension combined with peripheral vascular disease. 1. In simple hypertension, the blood pressure in the right arm is high while that in the left arm is not, whichever side has the higher reading, if the measurement is correct, hypertension can be diagnosed. The difference in blood pressure between the two arms is related to the anatomical and physiological differences of blood vessels. It is common that the blood pressure of the right arm is higher than that of the left arm in the normal population, and the difference in blood pressure between the two arms is generally not more than 10mmHg. 2. Hypertension combined with peripheral vascular disease, if the difference in blood pressure between the two arms ≥ 10 mmHg suggests the possibility of peripheral vascular disease, such as the left subclavian artery stenosis, the blood is not easy to pass through, resulting in the left arm of the low blood pressure; left brachial artery constriction, arterial confinement stenosis, narrowing of the lumen, resulting in a decrease in blood flow, low blood pressure. In the above cases, further angiography is recommended to clarify the etiology. Measurement of blood pressure in the left and right arms can help detect simple hypertension and early screening and identification of high-risk groups of cardiovascular and cerebrovascular diseases. If a significant difference in blood pressure persists between the arms, it may indicate peripheral vascular disease, and it is recommended to consult a doctor as soon as possible for detailed investigation so as to avoid delaying the condition.