Pulmonary function test is a routine examination of the respiratory system, mainly used to detect the degree of airway patency, lung volume size, etc. The test results have important clinical value for lung and airway pathology, disease prognosis, and evaluation of drug efficacy. There are many pulmonary function test items, and the instruments and equipment used for different items are different, and the test methods are not exactly the same. Generally, when doing pulmonary function tests, there will be a professional doctor for guidance. During the pulmonary function test, the subject needs to clamp the nasal cavity and breathe through the mouth. During the test, the subject needs to strictly follow the doctor’s orders, breathe calmly or slowly, and sometimes need to breathe quickly as required, and the breathing time should be according to the doctor’s requirements. Only when the subject fully understands the purpose and requirements of the test and actually follows the requirements can the objectivity of the test results be guaranteed. When using spirometry to measure lung volume and expiratory flow, the resting ventilation per minute is measured by calm breathing, and the maximum ventilation per minute is measured by forceful breathing. Generally, at the end of the calm breath, one inhales forcefully until one cannot inhale, and then exhales all the gas from the lungs as fast as possible. This procedure measures lung volume, spirometry, and ventilatory reserve, and provides an indication of whether the subject has obstructive or restrictive ventilatory dysfunction. Pulmonary function can also be examined with the aid of gas analysis with volumetric tracers and breath diffusion, depending on the physician’s instructions. After the test, the physician will interpret the lung function of the subject based on the results of the test. However, pulmonary function tests are not recommended for subjects with rib fractures or severe cardiopulmonary disease to avoid aggravating the burden on the lungs.