The purpose of this study was to explore the effect of support groups on the mental health and quality of life for mothers with autistic children. A quasi-experimental pre-post control group design was used in this study. The mothers had children without chronic diseases diagnosed as autistic based on Diagnostic and Statistical Manual of Mental Disorder-Fourth Edition (DSM-IV) and were their primary caregivers. The mothers were assigned to control or intervention groups based on their willingness. The 10 weeks of the support group programme served as an intervention. There were three waves of data collection: pre-test, post-test, and after 1 month follow-up. A total of 27 mothers with autistic children were assigned into experimental and control groups. In total, there were eight mothers in the experimental group and 19 mothers served as the control group. The results of this study showed that mental health had not significantly improved in the intervention group compared to those in the control group at the end of the first month during follow-up. However, the subjective well-being and employment status had an effect on their mental health. Only the subjective well-being had an effect on their quality of life. According to the results of this study, recommendations included (1) regularly promulgating a caregiver support group, (2) the advancement of training skills within the group, and (3) upgrading and promoting nurses ability to lead support groups in the future.