Border demarcation of nominated site for world natural heritage plays an important role in the application for world natural heritage. This work provides precondition for the application program and establishes scientific foundation for the future management and development of the world natural heritage. Based on theoretical analysis, this paper discusses how to apply RS and GIS technology in border demarcation of nominated site for world natural heritage. Influence factors, such as integrality of core values, human activities, boundaries of existing protected area and regionalism et al., are synthetically analyzed in advance. Based on the remote sensing image and topographic map of Kanas, RS and GIS technology is applied to identify the boundaries of the core area and buffer area. The results accord with the criterion of Guidelines for World Heritage. The core area guarantees the integrality of the outstanding universal values of the nominated site, and excludes human activities such as large-scale tourism that may threaten the outstanding universal values. The buffer area includes the traditional social economic activities, local communities and appropriate tourism, provides protective layers from the east, south and west and guarantees the integrality of visual range of the nominated site.