Background: This study increases our knowledge and understanding of factors influencing DNR decision-making by family members of terminally ill older adults in the emergency department. Emergency medical staff should keep abreast of the attitudes and wishes of family members and terminally ill older adults regarding DNR, and initiate DNR decision-making discussions as early as possible. Emergency nurses should pay more attention to the desire of family members to improve the quality of life of terminally ill older adults with DNR. Many terminally ill older adults depend on family members to make medical decisions in China. Many family members find it difficult to make do-not-resuscitate (DNR) decisions in emergency departments (ED). Currently, factors that affect DNR decision making by family members for older adults needing emergency care have not been well studied. Methods: This qualitative inquiry explores factors influencing DNR decision-making among family members of terminally ill older adults in ED. Semi-structured in-depth interviews were conducted for a 12-family member of terminally ill older adults at ED in China. Results: Results of the conventional content analysis showed that family members made DNR decisions based on a wide of reasons: (a) subjective perception of family members, (b) conditions of the terminally ill older adults, (c) external environmental factors, and (d) internal family factors. The findings of this study expand our knowledge and understanding of factors influencing DNR decision-making by family members of terminally ill older adults in ED.