Cognitive dissonance is a ubiquitous phenomenon which can be applied in various fields potentially. In this paper, we study cognitive dissonance through empirical analysis on social media platforms. Our study focuses on a recent “reversal event” - a topic or event experiencing a reversed development trend because of the new facts. Through statistical analysis and semantic analysis based methods, we found that (1) after the event is revised, the performance of the original followers were abnormal, which is consistent with the existence of cognitive dissonance; (2) the followers' attitude afterwards usually tended to maintain their previous behaviors. This research provides a primary building block towards the mental inference based behavior prediction for social media users, which is of great value for security related research issues.