Many people may think that measuring blood pressure is simple, but the number of people who are able to standardize the measurement of blood pressure is only in the minority. So how can we measure blood pressure correctly? First of all, the measured person needs to pay attention to the following matters: 1. Do not make position changes within 5 minutes before the examination, rest quietly and relax mentally. Avoid cold, exertion, pain, fatigue, eating, smoking and drinking coffee within 30 minutes before measurement, and should empty the bladder. 2, position: the measured person to take a sitting position, preferably sit back chair; bare right upper arm, elbow placed at the same level with the heart. If peripheral vascular disease is suspected, blood pressure should be measured in both arms during the first visit. In special cases, blood pressure can be measured in the lying position or standing position, the elderly, diabetic patients and those who often have postural hypotension, should also be measured in the standing blood pressure. Vertical blood pressure should be measured 2 minutes after the change from the prone to the standing position. 3. Requirements of the measurement environment: (1) The temperature of the examination room should be appropriate, and the ideal indoor temperature should be about 21 degrees Celsius. (2) Quiet and no noise. Measurers need to pay attention to: 1, the choice of sphygmomanometer: in the current mercury column sphygmomanometer has not been eliminated before the mercury column sphygmomanometer can be selected to meet the measurement standards for measurement. If a mechanical barometer or an electronic sphygmomanometer complying with international standards (BHS and AAMI) is used, it should be calibrated at the same time as the mercury column sphygmomanometer. Check the sphygmomanometer, i.e., close the valve of the air bag, pressurize and inflate, if the mercury column does not rise or there is a gap, it means that there is a leakage or insufficient amount of mercury, and the sphygmomanometer cannot be used. 2. Cuff binding: The cuff should be attached to the upper arm of the patient, and the cuff should be elasticized to accommodate two fingers. The lower edge of the cuff should be 2.5 cm from the bend of the elbow, and the cuff should be at the same level as the heart. The cuff should be at the same level as the heart, i.e., the brachial artery is flat at the fourth rib cartilage in the sitting position, the brachial artery is flat at the mid-axillary line in the supine position, and it is slightly abducted when extended. The chest piece of the stethoscope is placed at the brachial artery in the elbow fossa and fixed with slight pressure. The sphygmomanometer should be placed at the level of the heart regardless of the subject’s position. 4. The cuff should be of appropriate size, and the cuff airbag should wrap at least 80% of the upper arm. Most people’s arm circumference of 25-35cm, it is appropriate to use 13-15cm wide, 30-35cm long specifications of the airbag cuff, obese people or arm circumference should be used for large size cuffs, children with smaller cuffs. 5, the measurement of rapid inflation, the pressure in the airbag should reach the radial artery pulsation disappeared, at this time the pressure in the cuff is greater than the heart systolic blood pressure, blood flow blockage, and then rise 30mmHg, and then slowly deflate at a constant rate (2 ~ 6mmHg / sec). The eyes were leveled at the scale indicated by the mercury column. The rate of deflation is slower when the heart rate is slower. After obtaining a diastolic pressure reading, deflate quickly to zero. 6, in the process of deflation carefully listen to the Koch sound, observe the Koch sound of the first time phase and the fifth time phase of the vertical height of the mercury column convex. Systolic pressure readings to take Koch’s tone Ⅰ time phase, diastolic pressure readings to take Koch’s tone Ⅴ time phase (disappearance of sound). Children, pregnant women, severe anemia, aortic valve closure insufficiency or Koch’s tone does not disappear, to Koch’s tone Ⅳ time phase (tone) as diastolic pressure. 7, the unit of blood pressure in millimeters of mercury (mmHg), millimeters of mercury and thousands of Pascal (kPa) conversion relationship, 1mmHg = 0.133kPa. 8, the first measurement should be repeated 2 minutes apart, take the average of the two readings recorded. If the difference between the systolic or diastolic readings of the 2 measurements is >5mmHg, measure again 2 minutes apart and then take the average of the 3 readings.