The critical role of short videos platforms (e.g. Douyin, TikTok) in health communication during the COVID-19 pandemic has been widely recognized. To promote the “Health Code”, a Chinese version of contact-tracing App, to the public and gain the network effect for virus containment, the platform has developed a special hashtag #Health Code for the integration and dissemination of relevant information and knowledge, which has attracted various actors (e.g. authorities, main-stream media, influencers, users) to take part in this discursive construction practice. A content analysis of short videos with a hashtag #Health Code in Douyin (N = 353) was conducted. Empirical results showed that despite divergence among different actors, the discursive construction of the “Health Code” as a whole presented a supportive and constructive tone. Under a cognitive framework of “behavior-information-problem”, as well as the “language system” of short videos platforms, the “Health Code” was described as a lively and interesting social governance technology with gradually improving and expanding functions, which had a great impact on social life, but was also mandatory. The current study not only offers practical implications for promotion strategies for contact-tracing Apps, but also theoretically reveals how a short videos platform, as a public opinion field, influences people’s cognitive and discursive construction of a social governance technology through its affordances.