In the era of globalization, Sino-US relationship is currently the hottest topic, especially in the case of tensions in Sino-US trade relationship, and then the construction of national image of various countries becomes very important. Within the appraisal theory, this paper probes into the construction of national image from three perspectives, namely attitude, engagement and graduation. Through this study, the following findings have been highlighted. First, with reference to appraisal theory, the salient feature is that the text is emphatic. Emphatic words are widely used to enhance momentum of the expression and sharpen attitudes of the two anchors. Second, judgement is mainly used in the ATTITUDE system. Both sides prefer to construct the image of pursuing peaceful coexistence and wishing a better future for each other. Besides, they also incline to seek common ground while preserving difference. Third, heterogloss is the main application of the ENGAGEMENT system in the debate. The application of heterogloss can construct the national image of keeping objective and being fair by invoking a legal provision and using reference data. Fourth, emphatic words account for a high percentage in the debate according to the GRADUATION system. Both sides have a clear and sharp attitude to everything especially in face of the wrong perception of others. And they both construct the image of being gentle and modest, which shows the demeanor of a great country.