The invention discloses a novel use of endotoxin. The invention provides application of endotoxin in preparation of a product. The product has the effect of aggravating onset of characterization of a rabbit model with respiratory insufficiency. The onset of characterization of the rabbit model with respiratory insufficiency can be represented by at least one from (a) to (d): (a) aggravation of lung tissue damage; (b) increase of water content of lung tissue; (c) decrease of oxygen partial pressure in arterial blood; and (d) increase of partial pressure of carbon dioxide in arterial blood. The invention discovers the novel function of endotoxin and has actual value for preparation of the rabbit model with respiratory insufficiency.