Drought is the main disaster that restricts the social and economic development of Northwest China. Taking 51 prefecture level cities（autonomous prefecture or region）of northwest China as the research objects, by collecting socio-economic statistical data, meteorological data and RS image data, this paper constructs index system from the perspectives of exposure, sensitivity, and adaptive capacity. By using function model and obstacle degree model, this paper assesses urban drought vulnerability of northwest China, reveals the spatial differentiation pattern, identifies the main obstacles affecting urban adaptive capacity and proposes countermeasures. The results are shown as follows: the degree of exposure has similar characteristics with precipitation, the spatial regularity of adaptive capacity is not obvious in spatial terms, the sensitivity and vulnerability increase from east to west, and sensitivity pattern is similar to that of vulnerability. High vulnerability cities are mainly distributed in Xinjiang Province and northwest Gansu Province, according to the characteristics of vulnerability differences, the cities of the northwest China are divided into the following types: high-high-high-high, high-high-low-high, low-high-high-high, low-low-high-low, and low-low-low-low. The main obstacles that affect urban adaptive capacity include whether it is a water-saving city, the reservoir capacity and the per capita water resources.