The aim of this research is to analyze the level of sustainable tourism development in the Nam Du archipelago, Vietnam, from the perspective of the local people and tourists by the methods of descriptive statistics and explorer factor analysis. Questionnaires were conducted with a total of 128 local residents and 116 visitors. From the perspective of the local people, the research reveals that there are ten factors affecting sustainable tourism development in Nam Du archipelago, namely: (1) social security and traffic accidents, (2) economic development, (3) garbage status, (4) management of local government, (5) development planning and distribution of tourism benefits, (6) cultural value, (7) return of tourist and travel time, (8) satisfaction, (9) price of goods and services, and (10) warning and rescue system. However, visitors only identified seven factors affecting sustainable tourism development in Nam Du archipelago, including (1) garbage status, (2) management of local government, (3) economic development and social security and order, (4) satisfaction, (5) cultural value, (6) price of goods and services, and (7) rescue and recreation system. The paper also makes a comparison of the similarities and differences between the opinions of the two groups. The results of this study will benefit the management of local authorities, tourist agencies, local business owners and residents. Besides, this paper proposes some solutions for sustainable tourism development in Nam Du for the future.