The Theory of Chinese Medicine is a well-known classic work of medical history, which has been considered to be the work of XIE Guan, a famous Chinese medicine scholar in modern times. In recent years, a series of books of great historian LÜ Si-mian and related new historical materials have been published, including a work entitled Introduction to Chinese Medical Classics. It is similar to The Theory of Chinese Medicine in terms of the overall structure and contents of the text. Through careful study and examination, we can find that The Theory of Chinese Medicine is a supplement to Introduction to Chinese Medical Classics. According to the principle of respecting historical facts, it is necessary to claim that The Theory of Chinese Medicine was written by LÜ Si-mian and revised and enlarged by XIE Guan.