In the past few years, the phenomenon of post truth has become popular in Western countries. It refers to the fact that public emotions and personal beliefs have a greater impact on facts than the actual situation itself. The history of the post truth phenomenon can be traced back to the 1970s, but in recent years, due to the widespread use of digital and social media, the spread of fake news has become even more rampant. The phenomenon of post truth has become a new political culture, regarded as a manifestation of populist movements that resist elites. Currently, the post truth phenomenon faces some challenges. With the frequent occurrence of major public emergencies, new impetus has been provided for the popularization and complexity of post truth. After the COVID-19, people began to connect their personal situation with the health of the whole society, which further aroused the public's attention to the truth. However, studying post truth faces many challenges, such as how to explain the phenomenon of post truth, the motivation of fake news, and the persuasive strategies of news. In future prospects, the focus of truth after research may shift towards the role of emotions. Emotions are increasingly valued in social sciences. Understanding the relationship between emotions and facts will help to better understand post truth phenomena. Emotion is not only the opposite of truth or rationality, but also an important component of cognitive psychology and even a resource for social mobilization and integration. Further research on the role of emotional discourse will help reveal the social and cultural aspects of post truth phenomena. In summary, the evolution of post truth phenomena, current challenges, and future prospects are all important aspects of studying post truth. A thorough study of the history, motivation, and impact of post truth phenomena will help us better understand and respond to the challenges of post truth phenomena, and provide new directions for future research.