Abstract: The Jiuqianxi copper-gold deposit on the northern side of the Duolong ore concentration area has relationship with the Early Cretaceous Jiuqianxi rock mass, Quartz Monzonite Zircon is measured by LA-ICP-MS method which is mainly composed of Quartz Monzonite Zircon belongs to the Early Cretaceous, and a weighted mean ²⁰⁶Pb/²³⁸U age of 120±1 Ma (MSWD=1) for Zircon, and the age of its emplacement is basically the same as PuRang (116±2 Ma), Grass Mountain (122±1 Ma), DuoBuza (121.6±2.0 Ma) and Duolong (119～120 Ma) in the arc magmatic rocks of ZaPu-DuoBuza.This type of rock body has characteristics of Fe & Mg-rich mineral (such as amphibole, biotite and magnetite etc.) and Al-rich mineral (such as cordierite and white mica etc.), high SiO₂(63.66%～67.12%), high K₂O (43.60%～4.65%), high alkali (K₂O+Na₂O) (7.94%～8.96%), lower Al₂O₃ (1.83%～2.33%), medium CaO (2.94%～4.15%).Rittman index (σ₄₃) is 2.71～3.31, and the A/CNK value is 0.84～0.93.In the calculation of CIPW standard mineral, diopside is appeared, but corundum not appeared.the ACF diagram of sample is in the range of I type granite, Th and Y are positively correlated with the content of Rb, Pb is positively correlated with the content of SiO₂, and P₂O₅ is negatively correlated with the content of SiO₂, which indicate that the Jiuqianxi quartz Monzonite is I type granite with highly kalium & calc-alkaline metaluminous.REE (Rare Earth Elements) and trace element distribution curves are all in the range of the main early cretaceous granite in the southern margin of Qiangtang.The REE distribution curves of chondrite show the type of “seagull” with right-dipping, steep LREE distribution curve, flat HREE distribution curve, obvious Eu abnormity, no Ce abnormity.The original mantle normalized spider web appears as a fluctuating curve of right inclining.Relative rich in large-ion lithophile elements(LIL), such as Rb, Th, U and K etc., relative poor in high field strength elements (HFS), such as Nb, Ta, Zr, Hf, P and Ti etc..And indicating the typical geochemical characteristics of arc magmatic rocks.Combined with the regional geologic evolution analysis, it is concluded that Jiuqianxi granite is the product of partial melting of crustal materials under conditions of higher temperature, and in the background of northward subduction of Bangong lake-Nujiang oceanic crust.