Background: The coronavirus disease 2019 (COVID-19) pandemic has affected college students’ mental health and caused post-traumatic stress symptoms (PTSS). Event centrality is thought to play a key role in the development of PTSS, but it is not yet clear by what mechanism. Theoretically, event centrality may affect the retrieval of traumatic memories and further prompt post-traumatic cognitions to understand events, and so may in turn be associated with PTSS in college students. However, few empirical studies have examined the mediating role of post-traumatic cognitions in the relationship between event centrality and PTSS, especially among college students during the COVID-19 pandemic. Objectives: The objective of this study was to examine the mediating roles of post-traumatic cognitive factors (e.g. attention to negative information, catastrophizing, and rumination) in the relationship between event centrality and PTSS among college students during the COVID-19 pandemic. Methods: We recruited 1153 college students who completed the pandemic experiences scale, the centrality of event scale, the attention to positive and negative information scale, the cognitive emotion regulation questionnaire, and the PTSD Checklist for DSM-5 during the COVID-19 pandemic in May 2020. Results: In this sample of college students, event centrality directly predicted PTSS, and PTSS was also indirectly predicted by event centrality through attention to negative information, catastrophizing, and rumination. Conclusions: These findings support the existing literature on the relationship between event centrality, proposed cognitive variables, and PTSS, and shed light on the mechanisms underlying PTSS. Our findings also highlight the importance and applicability of targeted cognitive interventions for PTSS in college students during the COVID-19 pandemic. HIGHLIGHTS The COVID-19 pandemic has caused post-traumatic stress symptoms among college students. Event centrality is a risk factor of post-traumatic stress symptoms among college students during the COVID-19 pandemic. Attention to negative information, catastrophizing and rumination mediate the relationship between event centrality and post-traumatic stress symptoms.