Objective To investigate the status quo of posttraumatic stress symptoms in emergency department nurses and to examine any associated factors, thus to provide reference for formulating targeted prophylaxis and intervention measures to enhance nurses′ mental health. Methods A total of 571 emergency department nurses were selected from 22 hospitals in Chongqing and were surveyed using the Impact of Event Scale-Revised (IES-R), Mindful Attention Awareness Scale and Simplified Coping Style Questionnaire. Results The total IES-R score ranged from 0 to 88, with the median of 28. The prevalence of subthreshold posttraumatic stress disorder among the sample was 65.3%. The total IER-S score was negatively correlated with mindfulness and positive coping style, whereas positively correlated with negative coping style (P<0.05,P<0.01). Logistic regression analysis showed that mindfulness was a protective factor whereas negative coping style was a risk factor of subthreshold posttraumatic stress disorder in emergency department nurses (P<0.01 for both). Conclusion The level and prevalence of posttraumatic stress symptoms were relatively high in emergency department nurses. intrusion reaction was the most prominent symptom. Interventions on improving mindfulness and perfecting ways of coping can be taken to relieve posttraumatic stress symptoms in emergency department nurses.