Abstract: Drawing on John Searle-s Speech Act Theory, this article explores performances and functions of illocutionary force in discourse by conducting an in-depth dis course analysis of the Chinese classic drama Sunrise by Caoyu. The article concl udes that illocutionary force can be expressed through emotional meaning, conte xtual information and syntactic structures, and meanwhile illocutionary force le nds itself well to the revelation of the characters- psychological activities a nd helps to accelerate the coming of climax in a drama.