We collected fresh fecal samples of sympatric blue sheep (Pseudois nayaur, n = 297 dung piles) and red deer (Cervus elaphus alxaicus, n = 305 dung piles) during summer between July and August 2008 in 10 drainages of the Helan Mountains of Ningxia Muslem and Inner Mongolia municipalities. Two fecal pellets from each of 40 dung piles of both sheep and deer were mixed to form a single, species-specific composite sample. Microhistological analyses indicated that blue sheep consumed 35 plant species or genera from 19 families; Stipa spp., Poa spp., Seseli intramongolicum, Ulmus glaucescens, Agropyron cristatum were most common. Red deer fed on 18 plant species or genus from 11 families, and Salix microtachya var. bordensis, Populus davidiana, Ulmus glaucescens, Agropyron cristatum were most common. Graminoids comprised 69% of the diet of sheep, followed by forbs (18%), browse (8%), and shrubs (4%). Red deer fed mostly on browse (90% browse, 5% shrubs, 4% forbs, 1% graminoids). The Shannon-Wiener diversity index for blue sheep was higher than that for red deer. The Pielou uniformity index and food niche breadth of red deer were higher than those of blue sheep. Nine of the 43 identified species were eaten by both species, and the niche overlap index was 65.17%.