Huangdi's Internal Classic（Huang Di Nei Jing) encompasses multiple theoretical models based on the thinking and methods behind syndrome differentiation and treatment in traditional Chinese medicine（TCM).Successive generations of physicians have offered diverse interpretations of these models，gradually developing theories such as the six-meridian syndrome differentiation，qi-blood-body fluid syndrome differentiation，and Zang-fu syndrome differentiation.Although these models differ in perspective and the pathological concepts they explore，they essentially represent systematic summaries of similar or identical pathological states.Based on the “qi monism”，which views nutrient and defense as an integrated whole within the human body，there is an attempt to construct a syndrome differentiation model for nutrient and defense.This model seeks to reveal the relationship between the theories of nutrient and defense，qi-blood-body fluids，the five Zang organs，and the six meridians.Both physiological and pathological states of the body can be conceptualized through the nutrient-defense theoretical model.This nutrient-defense syndrome differentiation model can serve as a paradigm for the refinement of the TCM syndrome differentiation system.