This essay is mainly devoted to the relevance theory to explain the phenomenon of irony in Chinese. Firstly, the author introduces the definition of relevance theory and two principles of relevance theory (The cognitive principle of relevance and The communication principle of relevance). Then the focus is given to the application of relevance theory to irony. Next the author studies specific aspects of irony in Chinese by selecting them. It includes ironic expressions in internet phrases, literature works and cartoons. Finally, the authors summarize the use of irony in Chinese with relevance theory.