Spinel is an important mineral in mantle peridotite, and probably acts as a petrogenetic indicator of its host rock though it's low in volume. Chrome spinel are widely distributed in almost all rocks of the eastern Purang ultramafic rocks, Xizang (Tibet). In terms of mineralogy characteristics, spinels can be divided into two groups. One group exhibits euhedral to subhedral grains with dark brown color, the other one shows irregular and vermicular shape with light brown color. On the other hand, the spinels can also be divided into chromium rich spinels（Cr#>60）and aluminum rich spinels（Cr#<60）in the light of their chemical compositions. The former one mainly occurs in dunite, serpentinite and pyroxenite, and the latter species exists in lherzolite. However, the spinel in harzburgite is apparently different with regard to the morphology and chemical characteristics from that in other rocks, which indicates that it experienced complicated and variable geological processes. Based on the comprehensive studies on spinel mineralogy and chemical composition, we conclude that spinels in the Purang ultramafic rocks are of characteristics of both abyssal and supra subduction zone (SSZ) setting.