Mentoring, a kind of traditional mechanism for passing down knowledge and skills, is now becoming an organized field of practice in early childhood education contexts, not only globally but also in China. A variety of mentoring models have been implemented to facilitate the ongoing and continuous professional development of educators, including early childhood teachers. This qualitative case study focused on the impact of group mentoring on the professional development of four teachers in a Shanghai kindergarten. Within the theoretical framework of COP (Community of Practice), it was an investigation of how the group mentoring process, an alternative to traditional models of professional development, had an impact on the teachers in a changing early childhood education context in China. This study featured in-depth individual interviews with the four teachers (two mentors and two mentees), who are in the same mentoring group, and observations of their group mentoring activities. Data was coded and analyzed qualitatively. A few major themes emerged from the study: the teachers’ perceptions of the model, the benefits and challenges it brings, and its influence on their relationships and identity. The study aimed to gain insight into how group mentoring, a potentially optimal model, has exerted an influence on the teachers’ professional development. This study concludes with a discussion of the implications of the findings and areas for future research.