Abstract
This article, based on Zhang Delu’s synthetic theoretical framework for multimodal discourse analysis (MDA), conducts a multimodal discourse analysis on the documentary-The Lockdown: One Month in Wuhan. It is found that the documentary discourse involves two necessary modalities: language modality and image modality. The main relationship between them is complementary reinforcement. The common relationships between necessary modality and selective modality are interaction, primary and secondary, and context interaction. Although the overlapping relationship has little effect on the meaning construction of the discourse, its existence is justified in some cases. Through the analysis of the synergy of different modes, it is hoped that the article will provide some enlightenment for multimodal relationships in the meaning construction of documentary discourse.