Critical Metaphor Analysis integrates Conceptual Metaphor Theory, Critical Discourse Analysis, and pragmatics, and thereby connects discourse and society seamlessly through conceptual metaphor, which is one of the effective ways to analyze political discourse. This paper takes 31 Sino-US trade texts on the US government websites as data, and analyzes the legitimization of the US policy toward China from the perspective of Critical Metaphor Analysis. It is shown that the US government,through fabricating a political myth, constructs China as a BULLY, while the United States as a VICTIM, and Trump is constructed as a FIGHTER. This metaphorical system replaces complex political facts and becomes a way for Americans to understand the Sino-US trade war. It is hoped that this study may, through refining the Critical Metaphor Analysis method, enrich the legitimization research approach, and provide useful references for the construction of China’s foreign discourse system.