Flow sensor for pulmonary function testing, spirometer and testing method and application thereof

A flow sensor for pulmonary function testing, an application thereof in a spirometer, and a pulmonary function testing method. The flow sensor for pulmonary function testing has a hollow tubular structure and comprises: an expiration inlet (1), a first cone (2), a throat section (3) and a second cone (4) sequentially connected. A tube wall of the throat section (3) is perforated with a low-pressure tap (5), and a tube wall of the expiration inlet (1) or the first cone (2) is perforated with a first high-pressure tap (6). The flow sensor and the spirometer have high test sensitivity and accuracy, simple structure, and low cost of use. The compact structure facilitates the miniaturization, calibration and correction of a spirometer and is easy for after-sales maintenance.