From a linguistic point of view, synonym refers to a lexical phenomenon in which one object has different names. This is not a simple name multiplication, but a reflection of culture in language, which contains people’s thinking forms, values, cultural connotations and language characteristics and other deep meanings. This is a common language phenomenon from ancient times to the present. Based on the classificatory literature, this paper examines the phenomenon of synonym of animal words with the same Korean explanatory words as the starting point, which not only provides a good corpus for the study of the history of Korean vocabulary, but also for the study of the history of Chinese vocabulary. Through the comparison of animal vocabulary in classificatory literature, it is concluded that people often name animals according to their distinctive external characteristics, and the general selection rule is to give priority to visual perception based on shape, pattern, color, and habits. In vision, the shape of the animal is preferred, and in the form, the measurement and circle are preferred. These naming images tend to take in superficial features, reflecting that people’s understanding is developing from superficial to deep, from the outside to the inside. At the same time, it points out that the causes of synonym of the animal words include two categories: the sign-relational type and the cognitive type, reveals the regularity of the combination of “name” and “objective”, embodies the conditions for the production of Chinese words and the path of evolution, and provides beneficial enlightenment for linguistic research and cross-cultural communication. The research on the history of Chinese vocabulary will surely become the direction of future development with the research ideas and methods based on domestic materials and supplemented by foreign documents.