According to the modes of occurrence, nephrite can be divided into dolomite-related nephrite and serpentinite-related nephrite. In previous studies and exploration, serpentinite-related nephrite was hardly found in Hetian dolomite-related nephrite belt in Western Kunlun Mountains. During 2014~2015, lots of geological examination and collection of information concerning the location of serpentinite-related nephrite were carried out, and then some information about the occurrence of serpentinite-related nephrite orebody near the Altun fault zone was found in Qiemo County. Based on EMPA (electron microprobe analysis), XRF (X-ray fluorescence), ICP-MS (inductively coupled plasma mass spectrometry) and oxygen isotopic analysis, δ¹⁸O (15.2‰~15.4‰), Mg/(Mg+Fe²⁺)=0.83~0.89, Cr₂O₃=0.08%~1.65%, NiO=0.14%~0.22% and other geochemical data were acquired, which suggest a serpentinite-related nephrite origin. Wall rock of diorite also indicates that they formed at 267±14 Ma and 272±14 Ma, as shown by the SHRIMP U-Pb dating on zircons, which suggests the upper limit of the formation time of the serpentinite-related nephrite. Inverse isochronal age of Ar-Ar dating on biotite associated with serpentinite-related nephrite is 260.6±1.5 Ma. Both ages imply that they have relationship in genesis. Possibly due to the similar hydrothermal alteration of diorite, dolomite marble and tremolite, they have the close oxygen isotopic values (δ¹⁸O=14.3‰~14.7‰, δ¹⁸O=15.2‰~15.9‰ and δ¹⁸O=15.3‰). According to the chemical composition from bulk analysis of diorite (Cr=107×10^-6~155×10^-6, Ni=53.5×10^-6~85.8×10^-6), marble (Cr=2 036×10^-6~2 415×10^-6, Ni=1 403×10^-6~1 933×10^-6) and nephrite (Cr=867×10^-6~2 418×10^-6, Ni=960×10^-6~1 662×10^-6), together with the occurrence of chromite in nephrite, it is concluded that granodiorite and marble provided the ore materials for the formation of nephrite, and hydrothermal fluids were probably derived from both magmatic water and meteoric water in serpentine rock.