BackgroundNewly graduated nurses' lack of professional competence is associated with inadequate preparation during their clinical placement as nursing students. Clinical placement is a critical stage in the development of nursing students' professional preparedness. However, research on the trajectory of nursing students' professional preparedness during clinical placement has not yielded findings with the same specificity. ObjectivesThe aim of this study is to estimate differences in professional preparedness levels at different clinical placement stages, to identify distinct patterns of professional preparedness trajectories during clinical placement, and to evaluate predictors of these trajectory group memberships. DesignA quantitative longitudinal study. SettingsParticipants were recruited on a voluntary basis using convenience sampling at a tertiary hospital in Nanning, China. Participants224 senior nursing students were initially invited to participate in the study. A total of 178 nursing students successfully completed the follow-up assessments at baseline, as well as at 1 month, 4 months, and 8 months into their clinical placement. MethodsParticipants completed four online surveys, during which their professional preparedness level was measured using the Perceived Professional Preparedness questionnaire for senior nursing students. Professional preparedness scores at different time points were compared using one-way repeated measures ANOVA and latent growth modeling. Group-based trajectory model was applied to identify professional preparedness trajectories. Multiple logistic regression was adopted to determine the predictors of trajectory group memberships. ResultsThe entire sample of Senior nursing students experienced a significant increase in professional preparedness during clinical placement. The best-fitting group-based trajectory model delineated three distinct trajectories: low-slowly increase trajectory (27.53 % of sample), moderate-rapidly increase trajectory (47.19 % of sample) and a high-stably increase trajectory (25.28 % of sample). Male, good and excellent academic performance, and very high degree of professional interest are the predictors of the moderate-rapidly increase trajectory. While male, good and excellent academic performance, high and very high degree of professional interest and participating in medical-related part-time employment are the predictors of the high-stable increase trajectory. ConclusionsSenior nursing students exhibit different levels of professional preparedness throughout their clinical placement. Simultaneously, three different trajectories were identified among the sample of nursing students. Therefore, in future research, greater attention should be directed towards the professional preparedness levels of nursing students with different trajectories, and early identification and targeted interventions should be prioritized.