Lung function test is one of the necessary tests for diseases of the respiratory system, which has important guiding significance for the early detection of lung and airway pathology, assessment of disease severity and prognosis, evaluation of the efficacy of medication or other treatments, identification of the causes of difficulty in breathing, diagnosis of the location of the lesion, evaluation of lung function for the tolerance of surgery or labor intensity, and the supervision of critically ill patients, etc. The test includes ventilation function, ventilatory function and pulmonary circulation function. Lung function examination includes ventilation function, air exchange function, whoosh regulation function and pulmonary circulation function, etc. There are many examination items and measurement indexes. In the past, the lung function meter is mainly based on mechanical and chemical methods, which is cumbersome, time-consuming and laborious, and the detection error is large, limiting its wide application in the clinic, and the medical workers have limited knowledge about it. In recent years, with the development of science and technology, the emergence of new detection technology, especially the application of electronic computers, so that the lung function testing technology has been greatly developed, and its importance in the clinic is also more and more attention.