The mercury column sphygmomanometer is used as follows: i. The person being measured should be in a quiet state and rest for at least 5 minutes to reduce the error of measurement. Second, check the sphygmomanometer, turn on the sphygmomanometer, pull the switch and see if the mercury column is at zero scale. If it is not, it needs to be calibrated to avoid affecting the reading. Third, turn off the switch of the balloon, press the cuff with one hand, press the balloon with the other hand, inflate the cuff, and see if the mercury column will rise with it. If the mercury column is interrupted or does not rise, it suggests that the mercury column has an air leak or the mercury has decreased, affecting the blood pressure measurement. Fourth, when measuring blood pressure, the person being measured should take a sitting or supine position, keeping the upper limbs straight, and the elbows should be at the same level as the heart. Fifth, the gas in the cuff will be expelled, and the cuff will be placed on the wrist at 2-3 centimeters, with the appropriate degree of tightness. VI. The chest piece of the stethoscope, or the stethoscope, should be placed at the brachial artery of the elbow fossa during measurement. Seven, wear the stethoscope, close the balloon switch, inflate the cuff until the pulsating sound of the brachial artery disappears, then inflate it inward again so that the mercury column continues to rise by 20-30 mmHg, with both eyes looking level and parallel to the mercury column scale, open the balloon switch and exhaust the air at a slow rate. VIII. The systolic pressure is measured when a clear beating sound is heard during the mercury column drop. When the beating sound suddenly becomes weaker or disappears, the value is the diastolic blood pressure at this time. If the blood pressure value is too abnormal during the measurement, or if the person taking the measurement does not hear it clearly, multiple measurements should be taken. To measure blood pressure, usually at least 2-3 times, and then take the average.