Introduction: Nurses face many stressors in their job and profession. In addition to threatening various aspects of health can also affect their ability and cause an analysis of the quality of their performance. The purpose of this study was to evaluate the role of mindfulness-based stress-relieving training in reducing nurses' job stress Methods: This quasi-experimental study is a pre-test-post-test with a control group that was performed in 2018 on 270 nurses from different wards of Panj Azar Medical Training Center in Gorgan. Of these, 40 of them regarding inclusion criteria were randomly divided into control and experimental groups. Data collection tools were demographic information questionnaire and nurses' job stress questionnaire. The intervention was consisted of 8 sessions for mindfulness-based stress reduction holding once a week. Data was analyzed using SPSS software using both descriptive statistics (mean and standard deviation) and inferential statistics (Pearson correlation coefficient, Covariance and multivariate regression) at a significant level of p <0.05 Results: The results of this study showed that the mean scores of job stress before the intervention was not significantly different between the control and experimental groups (p <0.05) , but after the intervention the difference was significant (p <0.05). Furthermore, about 55% of the changes in post-test scores of job stress was related to the effect of mindfulness-based stress relief. This finding indicates that the implementation of mindfulness-based stress training program has been effective in reducing nurses' job stress. Conclusion: Given that nurses are exposed to high stress, the use of low-cost and short term therapy is necessary .The findings of this study showed that mindfulness-based stress training can be useful to reduce nurses' job stress.