"Phlegm" is the pathological product of the disorder of water and fluid metabolism in human body, and also an important factor inducing the occurrence of phlegm diseases. The production of phlegm is most closely related to the three viscera of lung, spleen, kidney and sanjiao. As a pathogenic factor, "phlegm" can often cause the obstruction of qi and blood circulation in meridians, affect the water-fluid metabolism, rise and fall of qi movement, and eventually lead to the occurrence of various difficult and strange diseases. There has always been a saying that "all diseases are caused by phlegm" , demonstrating difficulties in clinical diagnosis and treatment of these phlegm-caused diseases. Based on decades of clinical experience, Professor Xiong Jibai, master of Chinese medicine, puts forward an academic idea of "treating difficult and strange diseases from phlegm" , which has achieved remarkable clinical effect. Some representative medical records are presented in the paper, and they are hoped to bring some enlightenment to readers.