Lung function tests mainly include ventilation and gas exchange function tests, as well as some derivative tests. 1. The most commonly used indicators to reflect lung ventilation function are: lung volume, residual air volume, total lung volume, exertion lung volume, exertion expiratory volume in one second, maximum ventilation, and examination of small airway function. In addition, there are other indicators, i.e., spirometry, ventilation per minute, maximum ventilation per minute. 2. Ventilatory function examination is mainly to observe the diffusion function of the patient, and generally requires blood gas analysis. 3. Lung function also has derivative tests, including airway provocation test and airway diastolic test, also known as reversible test. Through the examination of pulmonary function can be earlier found lung and airway lesions, such as chronic bronchitis, chronic obstructive pulmonary disease, bronchial asthma and other diseases, can also be used to assess the severity of the disease, the effect of treatment and prognosis judgment.