The context is an important factor of Relevance Theory. “The context is a psychological construct, a subset of the hearer’s assumptions about the world.”（Sperber & Wilson, 2001: 15） The context comprises a huge amount of varied information about science and technology, religion and cultural factors. The context is a part of the cognitive environment of a person. In the process of communication, the same context that speakers and hearers know is named as a mutual cognitive environment. In the process of communication, with the aid of mutual cognitive environment, the hearer can understand the speaker’s communicative intention. The core of Relevance Theory is the optimal relevance principle: Communicative behaviors of Human produce an optimal expectation. The audiences have to find optimal relevance between the discourse and context of the communicator in the cognitive environment of two sides. Through reasoning, the audience can infer the implied meaning of the context, so as to obtain contextual effects. Finally, achieve the goal of communication.