The measurement of sustainable development capacity in Northwest China is an important issue. Based on the theory of ecological footprint，this paper calculates the per capita ecological deficit and water deficit in Northwest China for 2012-2016 years. The mean value of the former is 2.09hm²/cap and the mean value of the latter is 0.92hm²/cap. The deficit of ecological resources and water resources in Northwest China indicates that people’s demand for resources exceeds the supply of the resources. Then this paper evaluates the economic sustainable development capacity of Northwest China with the per capita ecological deficit，the ecological footprint for ten thousand Yuan GDP and the ecological footprint diversity index. The results show that the ecological footprint for ten thousand Yuan GDP in Northwest China has increased by 2.76%，and the ecological footprint diversity index is reduced by 4.88%. This shows that the utilization efficiency of the resources in Northwest China is decreasing. The stability of the economic ecosystem is weakening. This paper argues that the capacity of sustainable development of the northwest area is facing severe challenges，and the overload of the ecological environment has become an obstacle to sustainable development.