Introduction: The aim of this study was to investigate the relationship between cognitive avoidance, post- event processing and social avoidance among university students.Method: Four-hundred (221 female, 179 male) students were selected randomly. Subjects completed 3 standardized scales: cognitive avoidance questionnaire (CAQ), post-event processing questionnaire (PEQ) and the phobic reaction scale. Data were analyzed using Pearson correlation coefficient and stepwise regression by SPSS 16 software.Results: The results showed significant positive correlation between post-event processing and cognitive avoidance(r= /042; p< /0001). Also, correlation between thought suppression, thought substitution, transformation of images into thought and social anxiety were positive, but correlation between distraction, avoidance of threatening stimuli and social anxiety were not significant. Post-event processing and thought substitution was the best predictors and explained 16% of the variance in social anxiety.Conclusion: Social anxious people have cognitive processing about social relationships and post-event processing leads them to more anxiety and predict continuity of social anxiety. Awareness and cognitive therapy help them treat social anxiety and improve their social functioning.