Now the air pollution has become more and more serious, our lungs have also been very serious damage, hazy weather can be seen everywhere, haze particles for our body damage is very big, pm2.5 such toxic particles, if we breathe into the body, it will cause serious damage to the lungs, now lung malfunction phenomenon has been very common, more and more people appear lung The phenomenon of lung malfunction has become very common, and more and more people are developing lung diseases. But how can we see if we have lung dysfunction in our lives? Pulmonary function tests mainly analyze spirometry, force spirometry, and discrete function. It is beneficial for patients to know about the pulmonary function test so that they can be as relaxed as possible during the test, which helps to obtain more accurate test data. This test is only a functional diagnosis, not a pathological diagnosis. in the early stages, pulmonary function tests can be completely normal, and abnormalities in pulmonary function tests may occur only when the disease progresses. the most significant changes in pulmonary function in ILD are abnormalities in ventilation function and reduced gas exchange function. Ventilation is dominated by restrictive ventilation impairment, reduced spirometry, and a decrease in residual air volume with progression of the disease and a subsequent decrease in total lung volume. The ratio of 1sts time spirometry FEV1.0 to exertional spirometry FVC, i.e., the 1s rate, appears significantly elevated and supports the diagnosis of ILD if it has reached 90%. early stages of ILD may have small airway dysfunction, and its V50 and V25 are reduced after ILD forms fibrosis and V50 and V25 increase.