As one of the most widely used mindfulness‐based psychotherapeutic intervention techniques, mindfulness‐based stress reduction (MBSR) has emerged as an auxiliary or alternative technique for the treatment of post‐traumatic stress disorder (PTSD). This study conducted a meta‐analysis of the effect of MBSR on the changes in symptoms in PTSD patients. The final search was conducted on 10 December 2021, and 10 eligible randomized controlled trials were identified, including 768 participants. A quality assessment was conducted. Proportional sensitivity analysis and random effects meta‐analysis were performed, and the 95% confidence interval was calculated. Subgroup analyses were also conducted to identify moderators (e.g., features of population and intervention). Compared with the control condition, MBSR significantly reduced the symptoms of PTSD patients and had a moderately positive effect (g = 0.46, 95% CI: 0.31–0.62, p < 0.001). This was the case in people who suffer from PTSD for different reasons, indicating that MBSR is an effective treatment for PTSD symptoms in PTSD patients. It was feasible to implement MBSR interventions for PTSD patients caused by different reasons.