Cough is caused by stimulating the respiratory tract for various reasons. Chinese medicine believes that the lung governs qi and regulates breathing. Lung qi is simplified to the basic operation form by law propaganda, and the dysfunction of lung propaganda will cause cough. Cough is related to the lungs, but it can have other manifestations besides cough. Main qi and main qi of breathing lung include main breathing qi and main body qi. Su Wen Wu Zang Dai said: "All qi belongs to the lung." The fact that the lungs control breathing means that the lungs are places for gas exchange. Through the respiratory function of the lungs, clean air is continuously inhaled, turbid air is discharged, and innovation is brought forth, thus realizing the gas exchange between the body and the external environment and maintaining the life activities of the human body. "Su Wenyin Yang Ying Xiang Da Lun" said: "The weather is connected with the lungs." In fact, the function of lung controlling breathing is the concrete manifestation of lung qi function in the process of gas exchange: lung qi announces and turbid qi exhales; When lung qi drops, clear qi can be inhaled. If the spread and decline of lung qi are coordinated and orderly, breathing will be even and unobstructed. If the lung qi is not declared or the lung qi does not drop, the breathing will be abnormal, but the clinical manifestations are different. If internal drinking is triggered by external factors, airway obstruction and lung qi disharmony are mostly chest tightness, shortness of breath or asthma; If the liver fire is inflamed, the lung yin is damaged and the lung is depressed, it will lead to asthma and cough.