Abstract: The essential pragmatic function of political discourse is to participate in state affairs and then to influence and reform the society.This paper presents the metaphor phenomenon in political discourse.Through the illustration and discussion of metaphor examples, it aims to analyze metaphor's unique persuasive function in political discourse.There are four forms of persuasion, namely, ethos, pathos, logos, as well as pathos with logos.The paper holds that the effective and appropriate application of metaphor persuasion can deliver the abstract political message in a more vivid and appealing way so as to realize the pragmatic and social functions of political discourse.