Abstract: Subtitles, as a special type of texts, are characteristic of condensation, multimodality and audience-orientedness. In the light of the principle of optimal relevance, subtitling aims at conveying efficiently the movie author's communicative intention to the target audiences in the target language. In view of Relevance Theory, due to diverse features of English and Chinese, implicitation in E-C subtitling is an inevitable option from the perspectives of textual factors, target audience and linguistic structure.