Emergency work with regular exposure to traumatic events may cause a large burden of mental health consequences. Among the first responders, firefighters are generally said to have a larger risk for PTSD as they involve directly and indirectly with critical incidents and traumatic events as part of their duties. This systematic review will determine the prevalence of PTSD and identify factors which associated to the PTSD among firefighters. Methods Systematic search was performed for published articles from year 2007 till 2017 from five electronic literature databases and the PRISMA checklist was used for the workflow for article selection. A total of 12 articles were selected for final examination from a total of 188 articles screened. Results The prevalence of PTSD among firefighters are ranged from 6.4% to 57 %. Predictors are include demographic factor (age, educational level and marital status), job factors (years of service, rank, numbers of traumatic events, job stress, organization stress and burnout, occupational effort, internal locus control, resource availability, debriefing attendance), social support, post traumatic growth, comorbidity (anxiety, depression, work related injuries, chronic musculoskeletal disorder), coping style, resilience, personality, biological factor (adiponectin level) and physical factor (waist circumference, body mass index). Conclusions Various factors identified in different dimensions in order to promote the opportunities for firefighters to grow for a better outcome psychologically. Therefore, it is vital to recognize modifiable factors which are associated with PTSD and research need to focus more on these factors or predictors.