The study of Chinese vulgar characters is one of the important contents in the study of modern Chinese characters, and it is also one of the important contents in the study of the dissemination of Chinese characters. Based on the 81 poems and more than 300 folk characters in the Vietnamese Chinese document “Giới Hiên Collected Poems”, this paper explores the nature of Chinese vulgar characters and related issues. The nature of Chinese vulgar characters can be characterized from the perspective of Chinese character shape, structure and function: Vulgar characters are used by the civil community, with different forms of different forms, different components of the composition of the word, often used to record and correspond to the orthography of the Chinese character. Clarifying the nature of “vulgar characters” is of great significance to its ontology research, modern Chinese research, and Chinese character dissemination research.