Abstract: In combination with the trinocular perspective and framing theory， conceptual metaphors and their formation mechanisms in American political speech discourses have been interpreted from three levels in an analysis of two selected presidential speeches on climate change accord. Language forms of metaphorical expressions as the surface structure are induced “from below”， text meanings as the deep structure and metaphorical thinking are investigated “from roundabout”， and mapping and functions of metaphors are analyzed “from above”， showing the different positions and public policies on climate change for Democratic Party and Republican Party in the United States， and highlighting the systematic， continuous and dynamic metaphorical view of the two parties. Based on the surface and deep structure， the linguistic nature， cognitive nature and social nature of conceptual metaphors have been explored in depth from the trinocular perspective.

Key words: conceptual metaphor, trinocular perspective, political discourse, framing theory, climate change