The eco-environment is fragile in the Northwestern China. It is of great significance to conduct ecological security evaluation and analysis of driving forces. This study selects land use images and net primary productivity products to refine equivalence factors and yield factors. The improved three-dimensional ecological footprint model is used to calculate footprint size, footprint depth, and three-dimensional ecological footprint of Northwestern China from 2009 to 2017. The footprint size and footprint depth from 2009 to 2017 are spatially visualized. We adopt the ecological pressure index, ecological footprint diversity index, ecological coordination index, occupancy rates of capital flows and use ratios of stock-flows to describe quantitatively changes in ecological security. Finally, the extended STIRPAT model combines with the principal component regression model to analyze the main driving factors that affect the evolution of the three-dimensional ecological footprint. The results showed that:(1) the ecological footprint size from 2009 to 2017 displayed the tendency declining at the beginning and rising up later. The lowest value was 3.116 hm²/cap in 2009, and the highest one in 2016 was 3.796 hm²/cap. The ecological footprint depth has been increasing from 11.550 hm²/cap in 2009 to 19.031 hm²/cap in 2017. The three-dimensional ecological footprint has also been increasing from 6.006 hm²/cap to 9.760 hm²/cap during the study period. (2) From 2009 to 2017, the ecological security of the study area continued to deteriorate. Among them, the ecological security situation in Ningxia was severe, the ecological environment in Xinjiang and Shaanxi was fragile, the ecological security was relatively poor in Gansu, and the ecological security in Qinghai was good. The security status of the productive land types in different regions were different, but the similarity was that forest land was the safest and fossil energy land was the least safety. (3) The driving force analysis model indicated that the economic, social and technological development of the study area had a transmission mechanism for the occupation of capital. Per capita GDP, urbanization rate and population were the factors that increased the occupation of ecological capital. The energy consumption of per 10,000 yuan of GDP was a factor that alleviated capital losses except Xinjiang. Economic development still relied on the consumption of capital and energy. It needed to increase the level of investment in science and technology, improve the energy structure, and increase the efficiency of energy utilization. The industry should accelerate the transformation, improve the economic system, and reduce the dependence on capital.