This article discusses the essence and characters of the Traditional Chinese Medicine (TCM), as well as the formation and devopment of the TCM theory. TCM as a science, which is aimed to cure the sickness and save the patient, belongs to the category of applied science. It is a natural science with the characters of the social science and humanities. The experience medicine was the dominating content of the ancient TCM, while it progresses to the modernization TCM in the modern times. TCM theory took its source at a great deal of practice which was a long time fight with disease. From the accumulation and integration of the practice experience to the perceptual cognition and then sublimated to rational cognition, TCM theory widely adopted the ideology and method as well as the Weltanschauung of the ancient philosophy and humanities, and then gradually developed to the systemic TCM theory. This article emphasizes that the aim of the TCM modernization is entirely improving its ability of preventing and curing disease. The key of the TCM modernization is constant development and innovation, including the modernization of the herb and medicine as well as the theory of the TCM. This article will especially discuss the content and emphases in the modernization of the TCM theory, and some things that should pay attention to are also included.