Abstract: The Airag Uul Gold Deposit is located in the North Mongolia Cu-Au-Fe-Ni-P metallogenic belt of Western Mongolia.The ore bodies develop in hornblende monzogranite,biotite granite,plagiogranite during the Middle and Late Cambrian,and are displayed in vein,veinlike and lenticular forms.The alterations are mainly composed of potassic alteration,silicification,sericitization,and the silicification is closely related to gold mineralization.According to assemblage and formation sequence of ore minerals,the oreforming stages are subdivided into 4 stages:quartz-pyrite stage,polymetallic sulfide stage,pyrite-carbonate stage and supergene enrichment stage.Geological characteristics show that the Airag Uul Gold Deposit is medium-low temperature hydrothermal quartz vein type deposit controlled by NW-trending fault.