Abstract: The morphology and histology of the trachea and lung of Lipotes vexillifer Millerhave been studied. The lung of Lipotes is devided into two lobes, namely, the right and the left lobe.Lobulus pulmonis does not exist, and hilus pulmonis is in a high position. The tracheais divided into the right and left truncus bronchialis magistralis and bronches trachealis.The bronchialis trachealis branches off in a rather high position, which is similar tothat in Pontoporia. After entering the lung, the three truncus bronchialis magistralisbecome the trunk of arbor bronchialis. The distribution of the branches indicates, theexistence of lobes which consist of two in the left and three in the right. Tissue of cartilage is found throughout the trachea and the respiratory bronchiole.The epithelum of the trachea is a pseudostratified columnar ciliated epithelium mingledwith goblet cells. The epithelium of truncus bronchialis magistralis is simple columnarepithelum without any goblet cells. The small bronchus and bronchiole then becomespseudo-stratified columnar ciliated epithelium with a few goblet cells. The bronchiolegradually becomes simple columnar epithelium and cuboidal epithelium. No glands werediscovered in any part of the truncus bronchialis. At the entrance from the respiratorybronchiole to the alveolar duct, sphincter muscle exists. Muscles exist from all parts oftruncus bronchialis to the alveolar walls as interrupted on successive rings. The complete trachea is rich in elastic fibers.