Control of public discourse in China by official media has been the subject of several media-related studies. Few studies have been conducted, however, on the specific discourse strategies employed to exercise control. This study identifies five legitimization strategies of China's official media: legitimization through highlighting positive governmental actions, emotions, rationality, hypothetical futures, and quoting elites. It uses reports of the 2018 vaccine scandal in China published by Xinhua News Agency as examples to show how a top-down perspective is adopted to legitimize the ruling party and sustain social stability in a crisis. This is done in the hope of contributing not only to a better understanding of how legitimization is realized in practice in the sociopolitical context of an authoritarian society, but also to a deeper insight into the nature of China's official media discourse. Of the five strategies, legitimization through emphasizing the government's positive actions sets the tone for official news discourse; the other four serve to provide information and solve problems in the interest of the ruling party.