With the advancement of science and technology and the development of digitalization, multimodal communication has become the norm in people's daily life. Among these modalities, documentaries have gained the popularity of the audiences with their objective and vivid narrative style. During the Covid-19 pandemic, “Country and Home Sentiment” has once again become a buzzword dominating major media outlets and many documentaries on anti-epidemic themes are the epitome of this sentiment. Taking Together Against COVID-19 as an example, this article employs a combined methodology of quantitative and qualitative research to conduct a multimodal discourse analysis of the “Country and Home Sentiment” portrayed within the documentary. The study reveals that, in terms of symbolic resources utilization, the construction of “Country and Home Sentiment” in the film mainly relies on verbal narration and visual scenes, while the frequency of font and graphic symbols remains relatively low. Different types of multimodal synergies play direct or indirect roles in the construction process. This study, on the one hand, expands the dimensions of multimodal analysis within dynamic discourse; on the other hand, it showcases the Chinese people's sense of responsibility and mission in the face of significant public health events, which is conducive to the healthy social development.