Arable land in China is relatively scarce in terms of per capita, less than 40% of the world average. A large potential land area can be found for food production in Northwestern China, particularly with a low population density and relatively nice natural conditions. Therefore, it is necessary to identify the amount and spatial distribution of suitable land resources, thereby determining optimal cultivated land use for food production in China. In this study, a feasible model was established for the arable land resources to evaluate naturally suitable land potential for the cultivation, combining the comprehensive index method with limiting conditions and spatial analysis in geographic information system (GIS) from the standpoint of the suitability of land cultivation. 10 indicators were chosen from 4 factors in a multi-source raster dataset, including topography, hydrothermal, edaphic and ecological condition. The hydrothermal condition served as the baseline to distinguish the scenario of dryland and irrigated agriculture in different planting modes. An evaluation model of ecological risk was also established, including the risk of land use, soil erosion, and land desertification. The ecological security caused by land development was considered, where the potential arable land with better natural quality cannot partially assume the low risk of land development. Finally, the quantity, quality and spatial pattern of potential lands were assessed available for cropland, integrating the natural suitability with the ecological risk for cultivation. The results indicated that: 1) There was an obvious east-west differentiation in the distribution and spatial change of cultivated land in Northwest China. Specifically, the increasing area of arable land was distributed mainly in Xinjiang, whereas, the decreasing area was in Loess Plateau. 2) In dryland agriculture, the potential cultivated land was distributed mostly in the Tumochuan Plains on the south side of the Yinshan Mountains, where the specific area was about 0.2×104 km2, accounting for 0.06% of the total area of Northwest China. In irrigated agriculture, the most suitable land resource for cultivation was distributed mainly at the northern foot of Tianshan Mountain and the oasis along the Tarim River Basin, where the area was about 9.5×104 km2, accounting for 2.75% of the total area of Northwest China. Some land resources were required for the inevitable irrigation and soil improvement when planting crops, which were distributed mainly in arid inland areas, such as northern piedmont of the Tianshan Mountains, Tarim River basin, Shule River basin and eastern Inner Mongolia. There was a great potential for arable lands, if the irrigation water source was available, while the appropriate soil improvement measures were implemented in the future. The finding can facilitate the further scientific planning of water use and rational development layout of cultivated land resources, thereby relieving current land pressure for a better ecological environment.