Abstract: Online public opinion guidance is the top priority of the Party’s public opinion work. In hot events, the public opinion subjects are easily influenced by emotions and feelings, showing the symptoms of “post-truth” communication. Specifically, it is manifested as: the generalization of communication nodes leads to the privatization and fragmentation of truth interpretation; digital communication technology empowers the public to have an “unmediated” experience of truth; the instant stimulation of massive information easily erodes the public’s patience to restore the truth; social media hype about the truth feeds the public’s thirst for information. Online public opinion guidance not only needs to conduct pre-event early warning and judgment, and mid-event linkage and guidance, but also needs to carry out closed-loop guidance in the long tail period to prevent the accumulation and overflow of negative emotions in the “post-truth” communication, and to clean up moral biases and quickly restore damaged credibility. To achieve closed-loop guidance, the public opinion guidance subjects need to establish the concept of closed-loop guidance, implement the news practice requirements of full-process reporting, create and push historical files and public opinion briefs of major public opinion events, and at the same time focus on cultivating and improving the public’s media literacy to resist “post-truth”.