The invention relates to novel application of an exocarpium extract. The invention discloses application of an exocarpium total flavone extract to preparation of a medicine for preventing and treating PM2.5 particle-induced acute attack of a chronic obstructive pulmonary disease, a medicine for preventing and treating airflow limitation aggravation during an acute aggravation attack period of the chronic obstructive pulmonary disease, and a medicine for preventing and treating a high-airway reactivity and low-lung dynamic compliance disease of a respiratory system for the first time. Preferably, the exocarpium total flavone extract with the total content of flavone compounds being higher than 50% is used. Compared with the prior art, the invention has the advantages as follows: the exocarpium total flavone extract is simple in preparation method, low in cost and accurate in therapeutic effect; the exocarpium total flavone extract is a natural plant extract, is free of side effects, and can be used as preventive health food or therapeutic medicines.