Lung function cannot be tested on its own, but only through pulmonary function tests, which can tell the patient’s lung function. Lung function tests are performed to determine lung volume, ventilation, airway resistance, airway reactivity, and respiratory muscle strength. It can be used to determine the presence of obstructive ventilatory dysfunction, restrictive ventilatory dysfunction, diffusion dysfunction, and airway hyperresponsiveness diseases such as asthma. Secondly, the results of pulmonary function tests can be used to assess the severity of the disease, and based on the results, the corresponding treatment can be formulated and the prognosis of the disease can be judged. In addition, pulmonary function tests can be used to assess surgical tolerance and the likelihood of postoperative complications. Lung function tests are not suitable for everyone, such as uncontrolled severe hypertension, hemoptysis, severe pulmonary alveoli, recent myocardial infarction or stroke. If the patient has pulmonary discomfort, it is recommended to consult a doctor in a timely manner and complete the relevant examinations under the guidance of the doctor to clarify the cause of the disease.