Background “Crisis military deployment” was defined as a situation in which military personnel are suddenly ordered to duty to support an operation away from their home station and in a potentially dangerous environment. As a result of complex changes in the global political and economic landscape, military nurses are assuming an increasing number of crisis military deployment tasks. Moral distress has been widely studied among civilian nurses. However, little is known about the moral distress military nurses experience during military deployments (...) in crisis. Aim This review discussed the current state of research on the phenomenon, unique factors, specific sources, and measurement tools. Methods The scope of the study was defined using a framework developed by Arksey and O’Malley. Following English databases were searched: PubMed, CINAHL, Cochrane Library, Web of Science, and Embase, using MeSH terms and free word combinations; furthermore, Chinese databases: CNKI and CBMDisc, were explored using thematic terms from inception until January 20, 2023. Data were selected and defined by the inclusion and exclusion criteria and independently screened by two researchers. Ethical considerations The scoping review adhered to sound scientific practice and respected authorship and reference sources. Results Finally, 21 articles were included in the review. The moral distress of military nurses in crisis military deployments had unique and specific sources and reported positive aspects. The deployment environment and nature of the mission, responsibilities and obligations of military nurses, and the limited rights of patients were unique factors. Specific sources included third-party intervention, military triage, resource allocation, futile care, care of the enemy, and return to the battlefield. Military nurses in deployment reported positive aspects. They grow in their inner strength, build deep friendships and gain a greater sense of professional value. Conclusion It is important to understand the unique factors and specific sources of moral distress faced by military nurses in crisis military deployments and to identify the positive aspects. This research will help prepare military nurses for future deployments in advance by providing useful information to mitigate and eliminate moral distress. (shrink)