Background: Caring of the patients with mental disorders is a responsibility which brings lots of pressures and stresses to family members and lowers their quality of life. The current research aimed to study the effect of training coping strategies on the quality of life of caregivers of patients with chronic mental disorders. 
Methods: This study is a non-randomized clinical trial conducted on 94 caregivers of patients with chronic mental disorder. The samples were recruited by convenience sampling method and the eligible ones were put in the intervention and control groups. The data collection tool were demographics questionnaire and SF 36 life quality scale. The coping strategies were taught in eight 90-minute sessions, during 8 consecutive weeks (once a week) for 2 months in groups. The obtained data were analyzed using descriptive and inferential statistics by SPSS V. 20. 
Results: The caregivers were mostly female (62.7%) aged between 35 and 55 years. More than 80% of the study subjects were married. Most study subjects in both groups were housewives. In the intervention group, the physical functioning of quality of life before and two months after the intervention showed no significant difference (P = 0.877), but other areas showed significant increase two months later (P < 0.001). In the intervention group, the quality of life significantly increased two months after the intervention (P < 0.001), but it has declined in the control group (P < 0.001). 
Conclusion: Based on study findings, coping strategies training was effective in promoting the quality of life. Experts in family health education are in need to educate and train families. Therefore, we recommend the mental health system to promote quality of life via developing such specialized programs and facilities at educational and health centers.