Abstract：The clinical classification，diagnostic criteria，evaluation criteria of therapeutic effect，etc. are greatly different due to the differences of various syndrome differentiation methods when the methods are adopted. As a result，although the clinical effect of Chinese medicine in treating diseases is significant，it is still difficult to repeat and extend，and its significant therapeutic effect is difficult to be inherited by later generations. Based on these problems to be solved，the authors believe that the application of Prof. HUANG Huang's differentiation system of "Prescription- Disease- Individual" plays an important role in the guidance of treatment，and the authors systematically discuss the application of this system in the diagnosis of diseases. Taking insomnia as an example， this paper expounds that there are objective indications to apply differentiation system of "Prescription- Disease- Individual" in the diagnosis and treatment of insomnia， which has significant therapeutic effect.