Longshou mountains at the southern margin of Alxa block are famous for hosting the Neopaleozoic Jinchuan CuNi sulfide deposit, prospecting for CuNi sulfide deposits surrounding the Jinchuan ore deposit has long received much attention. The Xiaokouzi maficultramafic intrusions, located in the eastern segment of Longshou Moutnrain, consist mainly of serpentine rock, augite peridotite, olivine pyroxenite. Starshaped sulfide can be found locally. Sulfide contains pyrite and chalcopyrite, and no Niand Cu mineralization but parital mgnetitization were found in orebodies. The previous study suggests that the Xiaokouzi intrusions were likely the product of the same magma event with the Jinchuan maficultramafic intrusions. The lithogeochemical analysis in this study shows that the intrusions have fairly high MgO/FeOT values with m/f=5.31~8.74, which is higher than that of average Nibearing intrusions. The chondritenormalized REE diagrams and primitivemantle normalized trace elements diagram of the samples display a flat distribution pattern with low total REEs content, indicating olivine accumulation in the intrusions. Sr and Nd isotopic study yields εNd(t) values of 6.09~7.77, indicating the magma source is characterized by depleted mantle. Trace element ratios and modeling results also suggest that parental magma experienced weak contamination of middleupper crust. Single zircon U-Pb age of augite peridotite from the intrusions is 284.4±3.5 Ma. Compared with regional geology, the Permian igneous rocks may be related to the closure of the PaleoAsian Ocean, or an extensional regime after subduction.