The Dalaku'an mafic-ultramafic complex is located in the Late Paleozoic Karamilan arc zone, which is the southern active zone of the East Kunlun, and consists of lherzolite, wehrlite, olivine websterite, clinopyroxenite, plagioclase-bearing pyroxenite and grabbro. The olivine in the wehrlite and olivine websterite belongs to chrysolite with the Fo value ranging from 84.55 to 89.08, and the content of MnO and NiO ranging from 0.13% to 0.29% and 0.09% to 0.28%, respectively. The clinopyroxene belongs to diopside and augite with the content of MgO, FeO, CaO ranging from 15.12% to 16.98%, 3.84% to 5.34%, 21.10% to 22.95%, respectively. The mineral compositions of the Dalaku'an rock mass are different from those of the mafic-ultramafic cumulates from ophiolites, indicating that the Dalaku'an rock mass isn't a component of ophiolite but a continental intrusion. The mineral compositions of clinopyroxenes indicate that the parent magma belongs to the tholeiite series, which was formed in the continental margin rift during the subduction. There exist favorable conditions for the Cu-Ni sulfide deposit, as shown by the type of the intrusion, mineral chemistry and tectonic setting.