This study aims to carry out a critical discourse analysis of US President Donald Trump's tweets about China during the outbreak of the COVID-19 pandemic in the US. It investigates Trump's negative-other presentation of China on Twitter, a platform which has recently become popular amongst political elites, and which unmasks significant political ideologies and affiliations. Thirty tweets about China by Trump across five months; from the beginning of March to the end of July 2020, are selected for the analysis. The tweets are analyzed using Van Dijk's (1998) Ideological Square. The cognitive binary opposition between negative-other presentation and positive-self presentation unravels Trump's negative stance against China in contrast to the US under his presidency which is portrayed as powerful and heroic. The study also exposes Trump's discourse strategies and how he utilizes them to create this positive-self presentation and negative-other presentation. The results reveal that the self-other polarization is strongly evident in Trump's China tweets and that he employs various linguistic and rhetorical techniques such as lexicalization, metaphors, presupposition, repetition, loaded words and deictic expressions to achieve this strict polarization. He presents China as guilty, incompetent, a liar, a conspirator, an enemy of the people, a manipulator, and in the same tweets he presents himself as powerful and tough on China, as a savior of the nation and as the source of economic stability.