The current research is mainly conducted to explore the pragmatic functions of English rhetoric in public speech. To do this, methods of close reading and case studies are adopted. The research first reveals that the boom of public speech programs helps reexamine the art of utterance, during the delivery of which English rhetoric plays an indispensable role in shaping and expressing a speaker's opinions, and then, with Emma Watson's "HeForShe" as a case study, concludes the specific pragmatic functions of English rhetoric: parallelism helps strengthen opinions; irony shows dissatisfaction, disapproval or rejection; rhetorical questions invite no answers, but call for emphasis and sense of urgency; contrast describes difference(s) so as to show preference. Use of proper English rhetoric devices in public speaking as well as in daily life improves communicative effect and efficiency.