Background <p><?tk 2?>Patient incivility is a significant source of work-related stress for nurses, particularly in highly interactive departments such as internal medicine. Although such behaviours are low in intensity, they occur frequently, continuously depleting nurses’ emotional and psychological resources and impacting their well-being and the safety of nursing care. Existing research predominantly focuses on the impact at an overall level, lacking in-depth understanding of nurses’ individual cognition, coping strategies, and internal psychological processes within specific situations. This study aimed to explore the psychological and behavioural processes of medical nurses when encountering uncivil behaviours from patients, and to provide a basis for clinical management and support systems.</p> Methods <p><?tk 2?>A qualitative research method using Grounded Theory was adopted. Semi-structured in-depth interviews were conducted with 20 nurses recruited from the internal medicine department of a tertiary hospital in China. Interview data were analysed using NVivo 12 software, following the principle of constant comparison. A theoretical model was constructed through open coding, axial coding, and selective coding.</p> Results <p><?tk 2?>The analysis generated four core themes: (1) Situational Perception and Cognitive Appraisal: Nurses distinguish between emotional dysregulation caused by illness and purely malicious intent. (2) Diverse Coping Strategies: Including relational repair, boundary setting, cognitive reappraisal, and seeking external support. (3) Internal Negotiation: Reflected in the conflict between suppressing emotional expression and adhering to professional roles, the negotiation between professional ethics and personal dignity, and the trade-off between short-term and long-term outcomes. (4) Outcomes and Reflections: Manifested as changes in nurse-patient relationship quality, the dual outcomes of professional versus psychological capital, and the perceived absence of and demands for organizational support.</p> Conclusion <p><?tk 2?>Nurses’ responses to patient incivility constitute a dynamic, cognitively-driven psychological process. The core dilemma lies in the internal negotiation and resource depletion inherent in emotional labour. The effectiveness of individual coping strategies is limited, and systemic impact depends on the support of the organizational environment.</p> Clinical trial number <p>Not applicable.</p>