First of all, the environment should be quiet, the person to be measured should rest quietly for at least 5 minutes and try to relax, no smoking, no drinking and no holding urine for half an hour before the measurement. Second, the person to be measured should be in a sitting position with the elbow positioned at the same level as the heart. Third, the cuff should be of appropriate size, and the cuff airbag should wrap at least 80% of the upper arm. Fourth, the cuff is placed firmly against the upper arm, and the lower edge should be 2.5 cm above the elbow bend. Place the probe of the stethoscope at the brachial artery of the elbow fossa. V. Inflate the cuff quickly during measurement, and the pressure in the cuff should reach the disappearance of the radial artery pulsation and rise another 30 mm Hg, then deflate slowly at a constant rate (2-6 mm Hg/sec). The rate of deflation is slower when the heart rate is slower. Obtain a diastolic blood pressure reading and then deflate quickly to zero. Sixth, during deflation, observe the vertical height of the convex surface of the mercury column in the first and fifth time phases of the Koch tone. (The systolic pressure reading is taken from the 5th time phase of Koch’s tone). VII. The measurements should be repeated at 2-minute intervals and the average of the 2 readings should be taken. If the heart rate is irregular, especially in the case of frequent premature beats or atrial fibrillation, the blood pressure should be repeatedly measured 6 times to take the average value to reduce the error.