Succession is one of the important and valuable mechanisms in the progress and improvement of any organization, especially military organizations, and it can ensure the survival of the organization in line with the changes and environmental changes with the ability and competence of the employees. In fact, the succession of employees who are rangers; It is one of the main components of the military power of any country in facing any crisis. Currently, there is no pattern in this field; Therefore, designing this model is essential. This research was carried out with the aim of designing the pattern of succession of rangers in a military unit. To achieve this goal, a case study and a qualitative research method have been used. The statistical population of the research included the commanders and managers and academic elites of the Ranger units of the Islamic Republic of Iran Army, who were studied using snowball sampling, 25 people including 10 academic experts and 15 commanders and managers of human resources. The data collection method was field and the data collection tools were library studies and semi-structured interviews. In order to obtain the reliability and validity of the data, two methods of review of participants and review of non-participating experts were used in the research. Data analysis during three stages, open coding, central coding and selective coding, which indicates 104 general categories. The findings of the research showed that the obtained model can be used as a scientific and basic theoretical framework for the succession of rangers in a military unit.