Background <p>The COVID-19 pandemic has profoundly affected the mental health of nursing students, highlighting the importance of examining their mental health changes and recovery in the post-pandemic era.</p> Objective <p>This study aimed to explore the mental health changes and longitudinal relationships among nursing students after the full removal of COVID-19 restrictions through a longitudinal study conducted from December 2022 (one month post-removal, T1) to November 2023 (12 months post-removal, T2).</p> Methods <p>A total of 379 nursing undergraduates completed baseline and follow-up surveys, with all data collected using paper questionnaires. Descriptive statistics, paired sample T-tests, and Chi-square tests were used to analyze the data. Cross-lag analysis was used to investigate the longitudinal relationships between depression, anxiety, and post-traumatic stress disorder (PTSD) symptoms.</p> Results <p>The study demonstrated that scores for depression and anxiety symptoms significantly decreased over time, with prevalence decreasing from 72% to 50.1% at baseline to 51.7% and 31.2% at follow-up (<i>P</i> &lt; 0.001). However, PTSD symptom scores unexpectedly showed an upward trend, with prevalence increasing from 15.9% at T1 to 27.8% at T2 (<i>P</i> &lt; 0.001). In the cross-lagged model, depression (β = 0.61, <i>P</i> &lt; 0.001) and anxiety (β = 0.67, <i>P</i> &lt; 0.001) at T1 had significant cross-lag effects on PTSD symptoms at T2. Similarly, PTSD symptoms at T1 predicted subsequent depression (β = 0.33, <i>P</i> &lt; 0.001) and anxiety (β = 0.33, <i>P</i> &lt; 0.001) symptoms at T2.</p> Conclusion <p>The persistence of PTSD symptoms following the pandemic along with significant psychological stress, underscoring the need for targeted educational policies. Such policies should focus on enhancing post-disaster mental health recovery courses and fostering resilience among students.</p> Clinical trial number <p>Not applicable.</p>