This article examines the impact of short video platforms on the visibility of green diplomacy narratives, focusing on the green issues related to Vietnam on TikTok in China and the United States. By combining platform metadata, policy texts, and selected video keyframes, this study builds an analytical framework to trace how SDG-related targets are recognized, how cultural meanings are encoded in visual and textual narratives, and how these narratives circulate within recommendation flows. The results show that there is a differentiation in target alignment between Chinese and American narratives. Chinese content has a greater advantage in SDG 9, with an average effectiveness index of 0.679, higher than the United States’ 0.542; The US content is stronger on SDG 13, with an index of 0.660, higher than China’s 0.477. The recommended audit shows that Chinese sourced content accounts for 52.0% in the technology interest account, and American sourced content accounts for 0.45 in the climate action account, indicating that user interests will rearrange exposure opportunities. Cultural semantic analysis found that Vietnamese subtitles, local scenes, and community climate actions help enhance interactive feedback, while green infrastructure images strengthen technical credibility. This article reveals the correlation between green technology, climate governance, local culture, and platform algorithms, providing a basis for understanding the competition of digital public diplomacy in Southeast Asia.
