Objective To explore the development trajectory of professional identity in nursing students during clinical practicum and analyze its influencing factors, and to provide reference for taking measures to enhance nursing students′ professional identity. Methods A convenience sampling method was used to select 354 nursing students from two hospitals in Qingdao. Data were collected using a demographic information questionnaire, the Professional Identity Questionnaire for Nurse Students, and the Future Work Self-Salience Scale at the start of the internship, and then at 2, 4, 6, and 8 months during the internship. The latent growth mixture model and unordered multinomial logistic regression were used to explore the potential trajectories of professional identity and analyze its influencing factors. Results Three trajectories were identified:high-level stable group (33.90%), moderate-level declining group (38.70%), and low-level rising group (27.40%). Factors influencing the development trajectory of professional identity included the reason for choosing this major, average academic performance, and future work self salience (all P<0.05). Conclusion The professional identity of nursing during exhibits different developmental trajectories during clinical practicum. Mentors should help nursing during to establish clear future career planning and strengthen their professional identity.