Abstract:单, a Chinese character, appeared early in the history of Chinese characters and has a high frequency of use. The history can be roughly divided by the Warring States period and has undergone extension and narrowing in its functions. Throughout its history, it has had at least 28 different uses. Through a diachronic study of the functions of character, not only can new teaching methods be provided for the use of danand related words in Chinese language education and international Chinese teaching, but it can also be references for the compilation of relevant entries in dictionaries of Chinese language.