This paper summarized XIONG Ji-bo's clinical experience in applying the theory of "exterior of the lung and large intestine". XIONG believes that the connotation of the theory of "exterior of the lung and large intestine" lies in the large intestine in the lung, the lung in the large intestine, the lung lies in the large intestine, the lung and large intestine overlap. The realization of the theory of "exterior of the lung and large intestine" lies in the phase cause of qi movement, the correlation of body fluid metabolism, the connection of veins and the system of Yin and Yang and the five elements. In clinical application, people should be taken as the center and the pathogenesis should be grasped. Adopting the method of lung and intestine treatment or intestine and lung treatment always has remarkable curative effect.