Abstract: The age and geological setting of the Chihu molybdenum-copper deposit in the East Tianshan orogenic belt are still in dispute. According to the isotopic age data of the Tuwu-Yandong porphyry copper deposit in the same metallogenetic belt, the predecessors considered that the Chihu molybdenum-copper deposit formed during the Mid-Late Devonian and should be the product of Devonian island-arc volcanism and plutonism on the northern active continental margin of the Tarim plate. However, according to the zircon U-Pb concordia age of plagiogranite porphyry in the Chihu porphyry molybdenumcopper district, recently some researchers believe that the mineralized plagiogranite porphyry was emplaced during the Late Carboniferous and that the mineralization is related to calc-alkaline magmatic intrusion in the Late Carboniferous convergence stage on the southern active margin of the Kazakhstan-Junggar plate. SHRIMP U-Pb dating was carried out on zircons from mineralized plagiogranite porphyry in the Chihu molybdenum-copper district in this research on the basis of previous research. It yielded an age of 322+10 Ma (95% level of confidence), which suggests that the Chihu molybdenum-copper deposit formed during the Late Carboniferous and that the mineralization is related to Late Carboniferous hypabyssal intrusion of calcalkaline magma.