This paper aimed at the semantic extension of body language of Korean "입" and Body Language of Chinese "嘴, 口" by the perspective of cognitive semantics. Firstly, this paper made a contrastive analysis of the polysemous phenomena of "입" and "嘴, 口", and revealed what relevance their based on to semantic expansion.
Then, this paper examined the differences and similarities in the process of semantic expansion of the word "입" and "嘴, 口" based on the results of comparative analysis, and examined the reasons for the differences and similarities. It was found that in the process of semantic expansion, there were three reasons for the similarity. One was that the universality of human cognitive psychological process; the other was that the common human body structure and the same perceptual organs led to similar perceptions of body parts between Korea and China; the third was that Korea and China belonged to the same cultural circle and shared many commonplaces in system, culture, customs and production experience. The differences in semantic expansion were influenced by the number of semantic expansion, traditional national culture and system, language characteristics and cognitive differences.
At the end of the paper, on the basis of a specific classification system of noun meanings, the study gave meaning characteristics to the extended meanings of "입" and "嘴, 口", and classified them to reveal their tendency of semantic expansion. The study found that the semantic expansion of "입" and "嘴, 口" had the following tendencies: firstly, many extended meanings of body language had 'natural object/artificial object'. It well indicated that human beings recognized the outside world by their body and experience, and they transferred the characteristics of body parts to other active or inactive objects by some relevance. secondly, the extended meanings of "입" and "嘴, 口" had many characteristics of `attribute', which illustrated that body language, extended semantically through metaphor and metonymy into a state noun as an entity noun; Thirdly, many of the extended meanings of "嘴, 口" had the attribute meanings of "Classifier", which was about the fact that Chinese words were belonged to the semantic language.
Key words:body language, semantic expansion, metaphor, metonymy, generality, heterosexuality, tendentiousness