Delimiting the boundary of urban development can help to protect important ecological areas and natural resources, guide the efficient and orderly construction, prevent inefficient spread, optimize the spatial pattern of urban construction, and improve the level of land resource conservation and intensive use. This study defined a construction suitability index based on the economic and ecological perspectives. Through the calculation of the construction suitability index of landuse units and the setting of thresholds, the development boundary of Panyu District, a typical metropolis fringe town in Guangzhou City, was delimited. Under three different developing scenarios, three corresponding delimitation schemes were obtained. The results show that areas with high construction suitability in Panyu District coincidence with the current construction land. Some of the unconstructed landuse units with favorable conditions for development in the northeastern and western parts of Panyu, which are used as strategic land reserves by the local government, also have high construction suitability. The areas with low construction suitability mainly include mountain forests, water source protection areas, ecological corridors, permanent basic farmlands, and so on. In the resulting delimitation of development boundaries, ecological corridors are clearly identified. The construction land in Panyu is divided into several groups, and there is enough “ecological space” within the contiguous construction land. There are some differences in spatial distribution between the delimitation results and the current construction land, which can be used to guide and optimize the spatial pattern of urban construction and improve the level of urban land resource conservation and intensive use. The differences of the three delimitation schemes under different developing scenarios mainly lie in the allocation of landuse units with high or low economic value and ecological benefit at the same time. These landuse units locating in the “middle zone” and are not the first choice for construction, but can be included within the development boundary as an alternative if there is a need. The main conclusions of this paper are as follows: because of its own characteristics, the function of guidance, protection and optimization should be taken into account when delimiting the development boundary of metropolis fringe towns. The method of urban development boundary delimitation in this paper considers both economic and ecological aspects, and has certain flexibility, which is suitable for application in metropolis fringe towns.