As the use of ChatGPT in education becomes more prevalent, it is important to examine the potential impact on teachers' roles and identity. This study aimed to investigate how ChatGPT may shape teachers' roles and identity by conducting a thematic analysis of contents from WeChat posts that discuss the use of ChatGPT by teachers. The analysis focused on identifying themes related to the impact of ChatGPT on teachers' perceived self, pedagogical roles, and relationships with students. The findings suggest that ChatGPT may have both positive and negative impacts on teachers' roles and identity. On the one hand, ChatGPT can bring new possibilities to teachers allowing them to focus more on students' qualities and soft skills development and personalise feedback and assessment for students, which could reduce the workload of teachers and enhance their effectiveness. On the other hand, the use of ChatGPT may threaten the professional identity of teachers, leading to feelings of inadequacy or a loss of control over the teaching process. Furthermore, the use of ChatGPT may give rise to ethical issues in teaching and lead to a trust crisis between teachers and students. This study highlights the need for further research on the impact of ChatGPT and provides insights into the implementation of ChatGPT in education.