Background: Suicide among adolescents and young adults is a worldwide issue. Students spend much time in school, and school teachers play a critical role in identifying warning signs of suicide and detecting students at risk of mental health problems. However, limited studies discussed the teachers' perspectives on campus suicide prevention.Method: A qualitative study was conducted in January 2022. Purposive sampling was applied to recruit teachers from heterogeneous school systems in Taiwan. Due to the COVID-19 pandemic, we adopted the online focus group interview method. An interview guide with five open-ended questions was used. Data were analyzed using the content analysis technique.Results: A total of 18 teachers participated in this study. The participants expressed many challenges about mental health promotion at schools, such as lacking effective communication with other teachers and parents or lacking knowledge about suicide prevention and available mental health resources. They provided their perspectives on teaching materials and suicide prevention strategies, including the need for mental health promotion, mental illness literacy for both teachers and parents, and studnets' skill development regarding positive coping and emotional regulation, among others. Conclusion: A mental health promotion and suicide prevention guideline is urgently needed for the teachers. This guide would not only provide teachers with essential concepts and skills to alleviate stress or misunderstanding between the teacher-student-parent triad, but also offer multifaceted mental health strategies in teaching to enhance students' psychological well-being.