Urban spatial carrying capacity is the comprehensive support capacity of natural resources for urban development, which is of great significance in guaranteeing the sustainable urbanization. The middle-east section of North Slope of Kunlun Mountains in Xinjiang, China, is characterized by harsh climate and sparse population, whereas it is important for the initiative of the new Silk Road Belt because of its important location. Cities in this area have begun to take shape, and the implementation of the Silk Road Belt Initiative will inevitably stimulate the urbanization in this area. The extent to which the cities in this area will be supported by natural resources and how to fulfill the requirements of sustainable socioeconomic development needs to be investigated. In view of this, the present study evaluated the urban spatial carrying capacity and discussed feasible approaches that could support the sustainable urbanization in this area. The results show that 97.59% of the study area belongs to the low and relatively low levels of spatial carrying capacity for urban construction, and the area of medium, relatively high and high levels is 1.12 × 104km2, accounting for 2.41% of the total study area,mainly distributed in small clusters in the central alluvial fan oasis plains. Resource and environmental factors highly constrain urban construction, and low spatial matching of land and water resources, harsh climatic conditions and high risk of geological disasters are three major shortcomings. In addition, lagging transportation infrastructure construction and the resulting weak internal and external spatial connections also affect urban development. On this basis, the scientific arrangement of urban distribution, steady promotion of regional economic development based on local characteristics, further improvement of transportation infrastructure construction and strengthening the cooperation between the Xinjiang Production and Construction Corps and local governments are suitable approaches for sustainable urbanization in the study area.