In mainland China,internship plays an important role in pre-service teacher education which is held by normal universities or colleges.Student teachers,during the process of internship happened in elementary and secondary schools,apply instructional theories to practice and form their professional identity as well.The social interaction between mentors and student teachers is the mediation forming student teachers professional identity.This article,after collecting data from seven provinces in mainland China through a national project,analyzes the correlation between social interaction and professional identity of nearly 2000 student teachers.The research finds that there exists significant relevance (p<0.001) between social interaction and professional identity of student teachers.However,the reality of mentor-novice interaction is frequency-little,duration-short,mentor-centered and content-intensive,which result in general instruction rather than individual communication.Impacted by Chinese folk psychological features,harmonious and democratic interpersonal climate is useful to create the emotion energy between mentors and student teachers,which promotes the efficiency of problem-solving and total achievements.This research suggests that it is a critical approach to student teachers identifying by constructing appropriate interactive chains bonding mentors and student teachers physically and emotionally.