Abstract: In this paper, the authors conducted the study of volcanic rock geochemistry of the Kulapuheyan Formation-complex in the western part of East Kunlun Mountains. The results show that the values of MgO and FeO are1.12% and 0.63%, respectively, the values of TiO₂ and K₂O are close to the value of island-arc tholeiite (0.84%, 0.43%, respectively), the distribution of trace elements shows enrichment of Sr, slight depletion of HFSE Nb and Ta, and no significant fractionation or no fractionation of P, with rare earth pellet meteorite distribution curve showing good homologous nature (similar distribution curve variations). And it is consistent with the distribution trend of E-MORB. It is concluded that it was in an island arc environment and had the characteristics of islandarc tholeiite. It was derived from island-related enrichment mantle. The 688.7±5.1Ma represents the age of the captured crystal, and 483.4±3.3Ma is the age of the representative age of the basalts, and belongs to the Early Ordovician. In combination with its tectonic setting, geochemical characteristics and chronology, the authors hold that it was produced by the subtraction of the original Tethys Ocean subduction, and the original Tethys ocean subducted continuously at least until the Early Ordovician.