Objectives: The purpose of this study was to investigate causal metacognitive model for explaining the symptoms of war-related chronic Posttraumatic Stress Disorder (PTSD). Method: Current descriptive correlative study was performed on 80 subjects with war-related chronic PTSD selected conveniently among war victims who referred to Deputy of Treatment Affairs of Health and Treatment Office in the Ground Forces of Islamic Republic of Iran Army. The administered instruments included thought control, metacognitive beliefs and rumination questionnaires, PTSD symptoms checklists. Multiple regression model was used to test relational hypotheses and Overall, Parsimonious and Comparative fit indices to investigate the hypothesized and explained model of fitness through Statistical Package for the Social Sciences (SPSS) and Amos Graphic software. Results: The results of the structural equation modeling for explaining the symptoms of war-related chronic PTSD support the metacognitive model. Also, the finding of the overall fit indices of structural equation modeling (c²=1.82, GFI= 0.90, RMSEA=0.041) showed that the model is fit to data and closely related to the theoretical assumptions. Conclusion: Metacognitive beliefs through the mediation of thought control strategies and rumination influenced symptoms of war-related chronic PTSD and this causal model may facilitate case formulation and clinical treatment in veterans with this disorder.