The climate issue has become an important issue of common concern to all mankind. In the situation of International Climate Governance, China has gradually moved from a follower to a leader, providing important Chinese solutions for global climate governance. Carbon emission reduction strategy is one of the important strategies of China's Climate Governance, which provides an important action paradigm for the world.

Based on the theoretical framework of Network Agenda Setting（NAS）, this paper takes 816 carbon emission reduction reports on the twitter platform of China Daily from 2010 to 2020 and 1740 comments under its corresponding tweets as the research object, analyzes its topic construction form and user comment emotion on the social media platform, and discusses the fit and correlation between them, In order to explore the strategy of external communication of China's carbon emission reduction issues in the future.

The study found that at present, at the issue construction level of China Daily on carbon emission reduction, economic topics and political topics dominate in quantity, and governance effectiveness issues and governance initiatives show a significant growth trend, while the number of status quo reflection issues and knowledge popularization issues is small and late. From the perspective of audience cognition, the emotional tendency of Twitter users showed a significant positive trend from 2010 to 2020, but many users still have biased cognition on the issue of China’s carbon emission reduction strategy. Through Spearman correlation analysis of news sources, topics and users' emotional tendency, it is found that the public, NGOs, scholars and experts as news sources can significantly positive users' emotional tendency. Also, International cooperation issues, knowledge popularization issues and micro governance initiatives can promote users' positive comments.

This paper holds that, as a typical climate issue and global public domain issue, the external communication of carbon emission reduction needs to be placed at a higher visual threshold for strategic transformation. It is necessary to strengthen the construction of "discourse alliance" of carbon emission reduction communication, promote the integration with international issues, increase interesting and close popular science communication, and strengthen the distribution of persuasive and humane individual stories, To promote the construction of the voice of global governance.