Abstract: From a diachronic perspective, the prominence and specific connotation of the three basic discourse functions of Chinese tag questions are different in different development stages and under different contextual and semantic conditions. The specific performance is as follows: the origin of tag questions: "ideational function" orientation →subjective affirmation enhancement of tag questions: "textual function" orientation → deep subjectivization of tag questions: "interpersonal function" orientation. It can be seen that not only the grammatical structure is dynamic and emergent, but its discourse functions are also dynamic and development, and they are constantly changing, developing and enriching due to the continuous use of language. At the same time, using the dynamic and developmental perspective to examine the discourse function of the grammatical structure also helps to explain the functional demand drivers of the subjective and grammatical process of grammatical structure.