Ecological space distribution has important functions, and can provide a basis for making decisions regarding protecting the ecological security of national landscapes. How to define an ecological space has become a problem in ecological environment protection and management. Presently, ecological space delimitation technology is still in the exploration stage domestically. Ecosystem service functions and ecological sensitivity are the main indicators that reveal ecosystem health. Based on the ecosystem service functions and ecological sensitivity of ecosystem protection and decision-making management, the conflict between ecological systems and land use can be coordinated. This is conducive to restore and maintain regional ecosystem integrity and sustainability. In this study, the ecological space delimitation method was analyzed based on the importance of ecosystem service functions and ecological sensitivity in Nanning City, Guangxi Autonomous Region. Results showed that in the study area, the main ecosystem service functions were biological diversity maintenance and soil and water conservation function, followed by water conservation function. The comprehensive ecosystem service function was generally important, accounting for 42.32% of the research area. The main ecological sensitivity of the study area was soil and water loss, followed by stony desertification. The comprehensive sensitivity level indicated the ecological environment was sensitive, accounting for 85.44% of the total area. The preliminary delineation of ecological space in the study area was about 9325.27 km², accounting for 42.19% of the study area, and 76.59% of the area of ecological land in the study area. Forest land was the main land use type in the ecological space, accounting for 83.65% of the ecological space. The delineation of ecological space covered most of the ecological land. This method can be used in the delimitation of ecological space in space planning, which can provide auxiliary decision support for the planning scheme. In the next step, further discussion is needed to identify regional ecosystem service functions and ecological sensitivity mechanisms and capabilities from rich data sources and data accuracy. It is still necessary to combine ecological space with urban and agricultural spaces to comprehensively research the ecosystem. Further research on ecological space classification is necessary.