Background. With the prevalence of mental issues worldwide, more and more people are suffering from psychological torture. Mental Health Gap Action Program (mhGAP) has been introduced to improve the life quality of humans. Objectives. To explore and synthesize evidence of participants’ experience of mental health first aid (MHFA) training course. Method. Peer-reviewed qualitative evidence was systematically reviewed and thematically synthesized. Cumulative Index to Nursing and Allied Health Literature (CINAHL), Medical Literature Analysis and Retrieval System Online (MEDLINE), Psychological Information (PsycINFO), PubMed, Psych ARTICLES, Web of Science, Joanna Briggs Institute (JBI), and National Institute for Health and Care Excellence (NICE) databases were searched for the inception of the present study. The study’s quality was appraised using the Critical Appraisal Checklist for Qualitative Research of Joanna Briggs Institute (JBI) appraisal tool. All the participants who have attended the MHFA training course (excluding instructors) setting were included. Results. Six papers published between 2005 and 2019 were included for thematic synthesis. The review indicated that MHFA had been a positive experience for participants. Conclusions. MHFA courses can provide participants with professional knowledge of mental health counseling and improve their knowledge, practice, and attitudes towards their patients. Professional MHFA training courses should therefore be popularized and promoted among other populations.