Food habits of blue sheep, Pseudois nayaur in the Helan Mountains of China were studied from November 2003 to October 2004 to better understand diet composition, seasonal variation, and feeding habitat preference. Blue sheep consumed 41 plant species that contributed >0.01% to the diets. During autumn, winter, and spring, primary species consumed were Stipa spp., Ulmus pumila, and Poa spp. Blue sheep also showed the different preference for these plant species. Graminoids were the largest proportion of the diet (36.7–58.8%) throughout the year, followed by the tree and shrub categories. Sedges were the smallest proportion of the diet (0.7–7.1%). Among the four habitat types, blue sheep showed pronounced preference for montane woodland steppe. Differences in the diets of Helan Mountains blue sheep from those of blue sheep elsewhere may reflect adaptations for geographical range, vegetation, and other factors.