Abstract： This paper introduces Associate Chief Physician ZHENG Kai's clinical experience in treating internal diseases with Xiaochaihu tang. ZHENG Kai prefers to use Xiaochaihu tang to treat the disease syndrome of shaoyang whose pathogens lie in the half-exterior and the half-interior. According to ZHENG，this kind of disease is located in the half-exterior and the half- interior， and its pathogenesis is the dysfunction of acting as a pivot. In the treatment of it， ZHENG focuses on both pathogenic qi and healthy qi. In his clinical practice，he pays special attention to the symptoms of fullness and discomfort in the chest and rib- side， because it is the most powerful evidence for selecting Xiaochaihu tang. In his clinical treatment， Xiaochaihu tang is often modified according to different and varying clinical symptoms. The clinical application of Xiaochaihu tang has a great therapeutic effect on the treatment of cold，cholecystitis，mumps and otitis media.