This article first reviewed the theory evolution of viscera distribution in the surface of tongue and explored the cognitive origins of different tongue diagnosis theories by medical experts based on the conceptual metaphor theory.The literature review revealed that the theory of viscera distribution in the surface of tongue had undergone changes over time.For example，in Thorough Understanding of Cold Damage(Shang Han Zhi Zhang)，it is stated that “labial margin reflect the health of the spleen”，while in Yi Yi Ou Lu，it is mentioned that “the center of the tongue reflects the health of the spleen”，and in Yi Shu，it is described as “the left side and the right side of the tongue reflect the health of the liver and lungs，respectively”.In the current Diagnostics in Chinese Medicine，it is stated that “the sides of the tongue correspond to the liver，and the tip of the tongue corresponds to the lungs”.The different theories of viscera distribution in the surface of tongue represent different academic viewpoints and reflect the continuous thinking and improvement of medical experts regarding tongue diagnosis.Through an investigation of the theories of viscera distribution in the surface of tongue at different periods，it is found that the generation of these theories is based on metaphorical cognition，and the mapping of body locations onto the tongue plays a crucial role in the formation of these theories.The foundation supporting tongue diagnosis theory lies in the medical background and experiences of the medical experts.