Abstract: Ideological and political education emphasizes both ideological guidance and practical teaching. The realization of its educational value depends on teachers’ professional mission and educational commitment, while teachers’ professional identity is a crucial motivation for ideological and political education student teachers to devote themselves to teaching careers. Based on social cognitive career theory, this paper explores how educational internship affects student teachers’ professional identity. It selects 13 student teachers majoring in ideological and political education from a “Double First-Class” normal university in Beijing, and collects research data through in-depth interviews and autoethnography for qualitative analysis. The results show that educational internship influences student teachers’ professional identity through three paths: cognitive reconstruction, efficacy practice and value generation. Their professional identity is affected by micro individual factors, meso school factors and macro social factors, and the imbalance of responsibilities, rights and interests is the key cause of weakened professional identity. This paper further constructs a concentric circle model of relevant influencing factors, and puts forward optimization strategies of cognitive restructuring, practical empowerment and institutional guarantee to improve the internship mode for ideological and political education student teachers.