Definition and connotation of traditional Chinese medicine have experienced three great changes amid the development process over thousands of years. The first change is during the Spring-Autumn Period and the Warring States Period. Then traditional Chinese medicine refers to the core medicine of the Chinese nation; the second change is during the flourishing period of Tang Dynasty. The traditional Chinese medicine at that time refers to traditional medicine of Han nationality including medicine of imperial China, medicine of world center and medicine of Chinese nation; the third change is in late Qing Dynasty. Traditional Chinese medicine at that time is a system taking traditional Chinese medicine of Han nationality as the core, mainly relative to Western medicine.