In metropolises with high urbanization and being squeezed by a shortage of land available for urban development, it is of great significance to recognize important ecological nodes to designate as protected areas for controlling urban sprawl, and enhancing urban quality of life. In this study, ecological networks analysis has been designed, developed and tested with GIS technique for recognition of important ecological nodes. This paper applies this method to a model of urban district of Nanjing. The procedure was described as follows: (1) the potential ecological networks and ecological nodes were recognized using landscape resistance analysis and network analysis; (2) next, the ecological patches with high special service functions, such as those can protect rivers, provide recreational space, and mitigate industrial pollution, along the recognized potential ecological networks or around ecological nodes were screened; (3) finnaly, the ecological patches with high special service functions greater than a certain size were selected. The results showed that 7 important eco-patches were recommended to designate as permanent green space by law. Furthermore,some suggestion were given to guide the protection of the 7 important eco-patches in the correct direction.