Implicit rationing of nursing care is defined as the withholding of necessary nursing measures for patients because of a lack of nursing resources. However, no studies have explored the experience of decision-making about implicit rationing of nursing care in an intensive care unit (ICU). To explore the process of ICU nurses' decisions and judgement based on the conceptual framework of implicit rationing of nursing care. A qualitative study was undertaken between June 2020 and September 2020. The data collection methods were participative observation and interview. Eighteen ICU nurses participated in interviews. A thematic analysis was performed for the data analysis. The following five themes emerged: assessment of the condition and nature of nursing and time taken; strategies for setting personal priorities; plan implementation under mitigation strategy; existing nursing in reality; evaluation of the implementation of implicit rationing care. Nurses choose different strategies during plan implementation. In the absence of explicit guidelines on rationing nursing care, nurses often rely on intuitive and situational decision-making processes for setting priorities. Given the vulnerability of ICU patients and the absence of family caregivers, nurses bear a heightened ethical responsibility to provide care. Establishing a positive nursing culture is essential. It is both reasonable and effective to organize work by accurately quantifying workload, improving staffing levels and optimizing scheduling methods. These themes align with the decision-making process outlined in the conceptual framework and offer fresh perspectives. Nurses have a greater responsibility to provide care in an ethical manner and to increase awareness of the importance of holistic nursing care for the patient, that is to raise awareness of the importance of care that is often missed. Nurses actively adopt strategies to reduce implicit rationing of nursing care, including teamwork, organized nursing, working overtime and ignoring quality. The findings highlight the importance of creating a positive nursing culture that encourages nurses to adopt positive strategies.