Teachers' professional identity has an important impact on the career development of university teachers. The returnee teachers have both domestic and overseas study experience, so they show particularity in professional identity in China. This study adopted the mixed-methods approach to investigate returnee teachers' professional identity and the influencing factors. In the quantitative part, it took some returnee teachers from universities in China as samples, and in the qualitative part, it carried out one-to-one interviews with 8 returnee teachers. The results showed that the overall level of professional identity of returnee teachers was relatively high. Specifically, returnee teachers had the highest degree of identity in professional behavior inclination and the lowest degree of identity in the sense of occupational belonging. Besides, we found the professional identity of returnee teachers was affected by professional emotion, professional ability, professional expectation, professional environment and material conditions. Among them, material conditions and professional environment have greater influence on the professional identity level of returned teachers. We discuss the implications of these findings for research and practice in an educational context.