Vagueness is a linguistic phenomenon which ubiquitously exists in the communication of human languages.The use of vague language in teacher talk has an important effect on classroom interaction and teaching results.This paper,based on Verschueren’s Adaptation Theory,mainly explores the adaptability of vague language in English teacher talk in the communicative classroom context.The study shows that employment of vague language in English teacher talk adapts to the communicative contextual factors.Interpreting vague language in teacher talk is conducive to understanding the dynamic process of language use. Vagueness is a linguistic phenomenon which ubiquitously exists in the communication of human languages. The use of vague language in teacher talk has an important effect on classroom interaction and teaching results. This paper, based on Verschueren's Adaptation Theory, primarily explores the adaptability of vague language in English teacher talk in the communicative classroom context. The study shows that employment of vague language in English teacher talk adapts to the communicative contextual factors.Interpreting vague language in teacher talk is conducive to understanding the dynamic process of language use.