Professor Yin Huihe has developed the differentiation method of grasping the main symptoms, and formed the unique therapeutic system to treat many kinds of disease, which has creative thoughts and good clinical effects in the treatment of irritable bowel syndrome caused by diarrhea. Most of these diseases can be divided into two forms： one is induced by dampness retained in the intestine caused by spleen deficiency due to stagnation of liver qi, which is called painful diarrhea; and the other one is caused by the liver fire invading the stomach and leads to the pathogenic heat invading the large intestine, which is named heat diarrhea. The heat diarrhea is often treated by Wujiwan, which has been one of the important prescriptions used by professor Yin to practice the principle of grasping the main symptoms when treating the diseases.