Objective To examine the effect of a constructivism-based LEGO Serious Play intervention on role stress and professional identity of nursing students practicing in the ICU, and to provide a reference for innovation in clinical teaching. Methods A total of 110 nursing students practicing in the ICU were allocated to a control group （n=58） or an intervention group （n=52） chronologically.The control group received routine clinical teaching, while the observation group additionally received a three-stage ("role imagination-pressure identification-identity transformation") LEGO Serious Play based on constructivism.Before and after the intervention, the two groups were assessed using the Role Stress Scale and the Professional Identity Questionnaire.Meanwhile, semi-structured interviews were conducted with 12 nursing students in the intervention group. Results After the intervention, the intervention group reported significantly lower role stress score （34.23±9.36） compared with the control group （45.14±6.25）, and significantly higher professional identity score （63.96±8.28 vs. 49.76±5.05; both P＜0.05）.Qualitative analysis generated three themes:enhancing role awareness and engagement motivation, externalizing emotional experience and stress cognition, and strengthening professional identity and role transformation. Conclusion Constructivism-based LEGO Serious Play can effectively alleviate role stress and enhance professional identity among nursing students practicing in the ICU, and the students′ experience with this method is positive.