As a renowned poet in Taiwan and mainland China, Yu Kwang-chung is also a distinguished translator. Of all the translations being published, The Night Watchman (2004) stands out as a bilingual poetry collection, which contains stylistically versatile self-translation of many fine poems written by the poet in the last five decades. This paper aims at a study of rhythmic proclivity from the perspectives of Relevance theory. The term ”rhythmic proclivity” refers to the variation of rhythm patterns and particular rhetorical devices the poet employs to create musicality and to lay emphasis on certain words or phrases as communicative clues. It is observed that Yu succeeds in reaching optimal relevance by adding musicality with certain rhetorical devices to the target text. And the contextual effect it yields requires the target language readers' minimal processing effort to appreciate the poems' underlying significance. Evident examples are provided to illustrate the adequate contextual effects achieved in Yu self-translated poems.