Objective To explore the real psychological experience of ICU nurses in coping with the injurious behaviors of patients with delirium after cardiac and major vascular surgery，and to provide empirical evidence for the development of targeted psychological support and occupational safety protection strategies. Methods Using a descriptive phenomenological research design and purposive sampling，17 nurses in the ICU of a tertiary hospital in Zhejiang Province who had directly suffered from injurious behaviors of patients with delirium were selected as study subjects from January to February 2025. Data were collected through semi-structured in-depth interviews，and the Colaizzi 7-step analysis method was used to code，summarize，and refine themes. Results Four core themes and eight sub-themes were distilled. Four themes included the conflict between instinctive defense mechanisms and professional roles in stress responses（instinctive protective reactions and vigilance in threatening situations，behavioral restraint driven by professional responsibility），psychological states and professional belief crises caused by traumatic events（persistent psychological abnormalities triggered by traumatic memories，weakened and questioned professional value recognition），the demand for safety reconstruction during trauma recovery（the urgent need for security measures，the intense craving for workplace emotional understanding and response），and the integrated demand for a multi-dimensional support system（spiritual reliance on family emotional care，professional support from organizational systemic assistance）. Conclusion Managers should establish a phased intervention mechanism to address the multiple challenges nurses face when dealing with harmful behaviors of delirious patients：balancing instinctive defense mechanisms and professional restraint under stress，alleviating trauma-induced psychological abnormalities and reshaping professional identity，strengthening safety guarantees and emotional responses to support trauma recovery，and integrating family and organizational support to form a collective effort，thereby preventing the accumulation of trauma and ensuring the mental and physical health and professional stability of nurses.