Objective <p>To investigate the efficacy of situational simulation teaching (SST) in enhancing clinical thinking competencies among residents.</p> Methods <p>A randomized controlled trial was conducted with second-year residents (<i>n</i> = 121) during their rotation (May-August 2025). Participants were allocated to either an intervention group (<i>n</i> = 57, receiving SST) or a control group (<i>n</i> = 64, conventional training). Pre- and post-intervention assessments evaluated clinical thinking performance. Faculty assessments using the entrust able professional activities (EPAs) and Mini-clinical evaluation exercise (Mini-CEX) were completed within 2 weeks post-training, supplemented by resident satisfaction surveys.</p> Results <p>Both groups demonstrated significant post-intervention improvement in overall clinical thinking scores (all <i>P</i> &lt; 0.05), except for the “Ethics and Professionalism” domain in controls (<i>P</i> = 0.12).The intervention group outperformed the control group in total clinical thinking scores and all sub-dimensions (<i>P</i> &lt; 0.05), with higher EPAs scores, EPA pass rates, and Mini-CEX total scores (all <i>P</i> &lt; 0.05). Resident satisfaction (content, resources, interaction, and teaching methods) was also significantly higher in the intervention group (<i>P</i> &lt; 0.05).</p> Conclusion <p>SST significantly enhances clinical thinking development in residency programs.</p>