Abstract: Xiongjiashan Molybdenum deposit is another deposit which was found in recent years with considerable prospecting potential in northeastern Jiangxi-Wuyi uplift belt. S isotopic composition of sulfides from its ore is δ³⁴S=0.19～6.42‰, and 4.29‰ in average. Pb isotopic composition of molybdenite is ²⁰⁸Pb/²⁰⁴Pb=38.424～40.102,²⁰⁷Pb/²⁰⁴Pb=15.585～15.611, ²⁰⁶Pb/²⁰⁴Pb=17.975～18.432, and averages 38.822, 15.596 and 18.128 respectively. Through comparing the Pb composition with those of Caledonian and Yanshanian granites, and the S and Pb isotopic composition with those of Yinshan Pb-Zn-Ag deoposit and Dexing Cu deoposit, as well as discriminating by tectonic diagram of Pb isotope, it is concluded that ore formation of Xiongjiashan Molybdenum deposit is closely related with magmatic active of the Yanshanian granite, and the metallogenic material is principally derived from magmatic hydrothermal fluid. In addition to this, upper crustal rocks might have provided some metallogenic materials.