By analyzing the typical case of Professor Li Qi using Xiaochaihu decoction to treat tumors and related complications, this article summarizes Professor Li Qi's clinical experience and academic thought of using Xiaochaihu decoction. Professor Li Qi believes that the condition of tumor patients is complex, the key is to have a subtle insight, be proficient in syndrome differentiation, and hit the pathogenesis. As the representative of "he", the key of using Xiaochaihu decoction is to grasp the meaning of "he" . No matter upper or lower, surface or interior, qi or blood, zang or fu, those who are in disharmony with qi and blood and imbalance of yin and yang can go with it. It should be flexible in clinical practice, so as to improve the quality of life and prognosis of tumor patients.