Abstract:An ecological regionalization system was developed for the arid lands of northwestern China based on ecological and environmental factors, including climate, large-scale terrain features, landform, geology, vegetation, and soils, in combination with characteristics of social and economic development. The region was stratified into discrete geographical units of uniformity at three levels: Level I, the ecodomain, was based on climate and large-scale terrain features with consideration of the role of higher levels of regionalization and industrial development; Level II, the ecoregion, was based primarily on secondary landform, topography and large-scale vegetation types; and, Level III, the ecodistrict, was based on differences in local vegetation due to differences in geology and soils, as well as its eco-productive paradigm and potential future development. Based on this three-class system, we defined three ecodomains, 23 ecoregions and 80 ecodistricts. An ecoregional map of northwestern arid lands of China was drawn at 1∶1 million scale using GIS. The goals of the ecological regionalization classification were not only to develop a unique system of arid land ecological classification, but also to supervise local development and land use management to promote sustainable development of arid lands in northwestern China.