One of the main tests for lung function blowing is spirometry. Lung volume is the total amount of gas inhaled and exhaled to the maximum extent possible at one time. The normal value of lung capacity is about 3500ml for normal adults and 2500ml for women. For older people and infants, the normal lung capacity is lower than that of adults. Moreover, this indicator is closely related to the individual’s health condition, such as serious lung infection, pulmonary atelectasis, emphysema, etc., which may lead to a decline in lung function and make the normal value of lung function blowing lower. This time will suggest that the lungs inhale less oxygen and exhale less carbon dioxide, which may lead to the development of hypercapnia and hypoxemia, triggering respiratory failure.