Objectives <p>This study aimed to gain an in-depth understanding of mentors’ experiences with ISS in a top-tier hospital, to identify strengths, weaknesses, opportunities, and threats (SWOT) across the preparation, implementation, and feedback phases, and to provide practical recommendations for optimizing ISS practice.</p> Methods <p>A qualitative phenomenological approach was adopted. Using purposive sampling, 25 clinical nurse mentors who had participated in multidisciplinary ISS were recruited. Semi-structured interviews were conducted, and data were analyzed using Colaizzi’s seven-step phenomenological method. The SWOT framework was used to organize and present the themes across the preparation, implementation, and feedback phases of ISS.</p> Results <p>A total of 12 themes were identified across three stages. During the preparation phase, the themes included: (1) Strengths—structured preparation and formation of role identity; (2) Weaknesses—insufficient theoretical preparation and inadequate training mechanisms; (3) Opportunities—organizational empowerment and institutional support; and (4) Threats—tension between educational commitment and resource constraints. During the implementation phase, the themes comprised: (1) Strengths—the synergistic effect of immersive scenarios and reflective mechanisms; (2) Weaknesses—discrepancy between role expectations and teaching reality; (3) Opportunities—fostering learner collaboration and organizational momentum; and (4) Threats—conflicts between real-life settings and teaching order. During the feedback phase, the themes included: (1) Strengths—dual enhancement of positive feedback and teaching confidence; (2) Weaknesses—immediate feedback versus lack of long-term follow-up; (3) Opportunities—integration of technological tools and strengthening of instructional facilitation; and (4) Threats—resource depletion and increased role burden.</p> Conclusions <p>ISS promotes continuous self-reflection and professional development among nurse mentors, while supporting the integration of teaching into clinical practice. To improve ISS implementation, nursing education programs should prioritize pre-teaching preparation, allocate resources effectively, standardize debriefing procedures, and establish long-term evaluation systems. These strategies may help normalize ISS as a sustainable and high-impact component of nursing education.</p> Clinical trial number <p>Not applicable.</p>