Located in Tongren of Qinghai Province, the Longwuxia Gorge ophiolite lies at the juncture between West Qinling and Middle Qilian orogenic belts and is composed of mantle peridotite (dunite, serpentinized dunite), ultramafic cumulate units(clinopyroxene-peridotites, olivine-pyroxenites), mafic cumulate units(olivine-bearing gabbro, gabbro etc.) and diabases. All these units are in contact with faults and have been weakly altered. Polarized light microscope studies of thin sections reveal that the crystallization sequences is Ol→Cpx→(Opx)→Pl, consistent well with the marked SSZ-type ophiolite crystallization sequence. EPMA analyses of the minerals show that olivines belong to the chrysolite family, and clinopyroxenes mostly have the composition similar to that of augite and diopside. Discrimination diagrams based on clinopyroxene geochemical data indicate that ophiolite originated in a compression tectonic background related closely to volcanic-arc. REE concentrations of most samples assume the chondrite-normalized distribution pattern with weak LREE enrichment, which is very different from the pattern of MORB. The enrichment of large ion lithophile trace elements (e.g., Ba, Rb and Sr) and the depletion of Nb, P are similar to things of the subduction zone components. High field strength elements discrimination diagrams also prove the above conclusion. In addition, the ophiolite is supposed to have b een derived from a mature island arc tectonic environment, with the participation of some continental crust materials during the formation process.