Rapid urban expansion-especially, urban sprawl-has led to dramatic changes in land use/land cover. These land use/land cover changes, in turn, have caused the loss, fragmentation, and isolation of habitats of various species, and furthermore, brought serious negative influences on the sustainability of social, economic, and ecological development. It is important to convert non-construction land into construction land wisely and optimize current land use patterns for the purpose of sustainable development and human well-being. This paper, based on source-corridor ecological security pattern paradigm, puts forward a set of systematic methods through which reduction of construction land can be realized such that biodiversity conservation and sustainable regional development can be achieved. The Su-Xi-Chang region was selected as a case study representing rapidly urbanizing areas. Habitats of the little egret (Egretta garzetta) as well as its migrating corridors and their buffer zones were identified as critical sources of local ecological land. Based on these habitats and corridors, including the buffer zones, the local ecological security pattern was built. Plots of construction land that were located within the buffer zones of the identified critical ecological sources were the plots to be reduced, i.e., they needed to be transferred into the same land-use type as that of habitats or corridors, to improve the current quality and connectivity of habitat networks. The results show that within the region, the total size of reduced construction land was 10170.44 hm², among which sizes of urban land, rural residences, and transportation land-use types were 5408.38, 4017.96, and 654.10 hm², respectively. Furthermore, based on the ecological security pattern paradigm, different ecological sources and their corresponding corridors and buffer zones could be identified from perspectives such as importance, vulnerability, sensitivity, and connectivity. Then, the regional ecological security pattern could be identified through overlapping plots of these critical ecological sources. Based on the order of importance of the different perspectives, the identification of construction land plots in the buffer zones from one perspective could then be repeated from a different perspective with less importance than the former, and the two steps could be overlapped-such that new plots of construction land could be recognized and converted into non-construction land-use types (i.e., reduced construction land)-resulting in improved local ecological security. The method generated in this study is suitable for regions with different characteristics, and can also be applied in optimizing scenarios where the total amount of construction land increases or remains unchanged. It is necessary to emphasize that the order of importance of different perspectives of ecological security of one region may not be the same as others; hence, the result of selected local critical ecological sources will not be the same among regions and cannot be simply copied from one region to another.