The main principle of the sphygmomanometer is the process of air-pressurized compression of local arteries, which prevents the local arteries from pulsing by applying pressure and measuring the pressure of blood flow during the period. It can be categorized into two types: the auscultatory method and the oscillometric method. Blood pressure measurement methods are direct measurement method and indirect measurement method. Generally choose the indirect measurement method, that is, we usually use sphygmomanometer measurement. Methods: rest quietly for 5 minutes, take a sitting position or supine position, expose the upper limb, make sure the elbow, sphygmomanometer and heart are at the same level, wrap the cuff flatly under the upper arm 2~3 cm from the elbow socket. Find the brachial artery pulsation place stethoscope, inflate until the brachial artery pulsation disappears, then inflate 20~30mmHg, deflate, hear the first sound for systolic blood pressure, and the last heard for diastolic blood pressure.