Looking at the tongue is an important part of traditional Chinese medicine. The saying that "the tongue is known from the heart" and "the tongue is the seedling of the heart" directly reflects the close relationship between the tongue and the heart. People think that the tongue is both a "seedling of the mind" and a "seedling of the body". Its theoretical basis is that the zang-fu organs are connected with the tongue through meridians, reflected on the tongue through gasification function, mapped on the tongue through holography, and presented on the tongue through the ups and downs of qi, blood and body fluid. At the same time, it is pointed out that the tongue is the seedling of the body and plays an important role in clinical health preservation and disease prevention.