Traditional Chinese medicine believes that "whoever has internal causes must have external causes", that is, different types of constitutions have different affinity for diseases. On the basis of long-term medical practice, ancient physicians widely applied the theory of Yin-Yang and Five Elements in the medical field, used it to explain the origin of human life, physiological phenomena and pathological changes, and to understand clinical diagnosis and prevention, which became an important part of the theory of traditional Chinese medicine and had a far-reaching impact on the formation and development of the theoretical system of traditional Chinese medicine.