The relationship between the lungs and the large intestine through the meridians constitutes an epiphenomenal relationship, which can be elaborated and understood from two aspects, namely, physiology and pathology. The physiological connection between the lungs and the large intestine is mainly reflected in the interaction between lung qi purging and conduction in the large intestine. Lung qi purging descending, smooth qi, downward dispersal of fluid, promote the conduction of the large intestine, conducive to the discharge of dregs. With normal conduction in the large intestine, the dregs go downward, which is also conducive to the purging and descending of lung qi. The lungs and the large intestine can also affect each other pathologically. Lung gas congestion, loss of purging, gas does not go down, not down to the Jin, can cause viscera gas, intestinal dryness and constipation. If the colon real heat, stool dry knot, conduction is not smooth, visceral gas blockage, can also affect the lung gas declination, chest tightness and coughing. Therefore, the treatment of intestinal constipation, we must also nourish the lung fluid, and lower the lung qi. Treatment of chesty coughing lung disease, but also to unimpeded the large intestine. If you feel unwell, you should go to the hospital in a timely manner, after a clear diagnosis by the doctor to arrange the treatment program, do not adhere to the theory of self-treatment, so as not to delay the condition.