Abstract: Halliday divides grammatical metaphors into ideational grammatical metaphor and interpersonal grammatical metaphor on the basis of its functions. Yet many scholars at home and abroad have argued that there do exist the third kind-textual metaphor. Exemplified by the commencement speeches of Harvard University from 2007-2012, the author will present the application of textual metaphors and illustrate how its five types: thematic equatives, predicated theme, thematic comment sentence, passive sentence and compound noun phrase, are used in the samples.

Key words: Grammatical Metaphor; Textual Metaphor; Commencement Speeches

摘要：韩礼德从功能上将语法隐喻划分为概念语法隐喻和人际语法隐喻。然而许多国内外学者提出有第三种隐喻的存在，语篇隐喻。作者以2007-2012年哈佛毕业演讲为例，探讨其中五种语篇隐喻，即主位同等结构，谓化主位结构，主位化评论句，被动语态句和名词复合词组在所选演讲语篇中的运用。

关键词：语法隐喻；语篇隐喻；毕业演讲