Purpose: The present research was conducted with the aim of identifying the role of school principals in the formation of teachers' professional learning communities. Method: This research was conducted using a qualitative method through a semi-structured interview. The participants of the research were 20 principals and expert teachers who had experience working in educational groups and were known for success in their professional performance. The data obtained from the interview were classified and analyzed using the checklist tool. Data synthesis has been done in three levels: open coding, central coding and selective coding. Findings: According to the findings of the research, 18 indicators were identified in the selected code "principals' strategies in forming professional learning community". These open codes were categorized into 6 components. Also, 11 indicators were identified in the selected code "principals' beliefs in the formation of professional learning community" and categorized into 4 components. Conclusion: The results of this research show that "program-oriented", "supportiveness", "integration", "seeking cooperation", "empowermenting" and "continuous monitoring" are principals' strategical components for the formation and development of professional learning community; and "belief in long-term comprehensive, local and result-oriented approach", "adherence to participatory leadership", "belief in the ability to create change and continuous improvement" and "knowing the necessity of commitment, creativity, expertise and experience as managerial prerequisites" are the components of principals' beliefs in the formation of professional learning community.