Abstract: The Bielisaibei iron deposit is a small deposit recently discovered in the East Kunlun metallogenic belt. Based on an analysis of the geological background and ore deposit characteristics, the authors studied petrological geochemistry of the deposit and conducted LA-ICP-MS zircon U-Pb dating of the quartz diorite which is most closely related to mineralization. According to the results obtained, the LA-ICP-MS zircon U-Pb age of the quartz diorite is 242.9 ± 0.6 Ma (MSWD = 0.6, n=22), and the major elements of the quartz diorite have the data SiO2 (51.98%-63.83%), Al2O3 (14.55%-17.57%), Na2O (2.95%-4.21%), and K2O (1.60%-3.83%), indicating that the quartz diorite belongs to the metaluminous medium-high potash calc-alkaline series. Other characteristics of the quartz diorite include moderate ΣREE values, enrichment of LREE, moderate negative Eu anomalies, strong enrichment of K, Rb, Th, moderate enrichment of Ta, Nb, Zr, Hf, Ce, Sm, insignificant enrichment of Ba and Sr, depletion of P and Ti, and somewhat higher Sm, Y and Yb values than chondritic values, suggesting that the magma was dominated by crustal rocks.