|Abstract:The Sinongduo Ag-Pb-Zn deposit is the first discovered medium-large scale low-sulfidation hydrothermal deposit in the Linzizong volcanic rock of the Gangdese metallogenic belt. There are various mineral assemblages and structures, and this deposit has the typical characteristics of hydrothermal mineralization. The periods of the mineralization in this deposit can be mainly divided into three stages: (I) sphalerite-chalcopyrite-enargite-pyrite-quartz stage, (II) galena-sphalerite-silver mineral stage, (III) pyrite-quartz-calcite. Through the field investigation, geological logging, microscopic observation and the electron microprobe analyse (EPMA), this paper have studied the occurrence of the silver in Sinongduo deposit. The results acquired have shown that the silver primarily exists in the form of independent silver minerals. However, the other sulfides just have merely silver, such as the sphalerite, galena, pyrite and chalcopyrite. The silver minerals mainly include peaceite, argentite, pyrargyrite, akanthite and native silver, which occur in the fissure of the Fe-Mn carbonates, jasper and the early sulfides. Moreover, several silver minerals exist in the form of being wrapped in the sulfide. Some invisible silver can be found in the enargite. The silver mineralization is mainly formed in the No.II metallogenic stage and the silver is carried in the form of sulfur complex migration. With the change of physical and chemical conditions that belongs to the ore-forming fluid, the silver precipitate and form different kinds of silver minerals.