Abstract
Aristotle’s famous theory on rhetoric (Logos, Pathos, Ethos,) is a cornerstone in public speech. The paper would focus on Ethos and its implement in rhetoric devices in public speech. It would make an analysis on Michelle Obama's farewell speech at the White House on its rhetorical applications in lexis, syntax, phonetics and gestures. From the paper, the readers can obtain some experiences for appreciating public speeches and the teachers can find more effective ways in composition teaching of public speech.