Improving the quality of public administrative services in the field of social insurance is a priority for countries in the context of rapid population aging. With a case study in Rach Gia City, Kien Giang province, the article aims to study factors affecting people's satisfaction with social insurance payment services in light of administrative reform being prioritized by the Government of Vietnam. The study conducted a survey of 228 social insurance recipients, who have been carrying out administrative procedures related to social insurance payments in communes and wards of Rach Gia City. The results show that there are five factors affecting people's satisfaction on the quality of public administrative services on social insurance, including administrative procedures, staff and civil servants’ attitudes, professional expertise, access to services, and physical facilities. Among them, physical facilities and the level of easy access to services have the greatest influence on the satisfaction of people using social insurance services.