The Jiagangxueshan W-Mo polymetallic deposit in Xainza County of Tibet is located in northern Gangdise belt, and its metallogenic time is Miocene. The deposit is closely related to the monzogranite located at the center of the deposit temporally and spatially. Greisenzation is the commonest wall rock alteration, and the positions where there exist intense greisenzations usually have relatively good mineralization. The types of orebodies are mainly greisen-type and subordinately quartz vein-type. Moreover, mineralization styles are dominantly veinlet and dissemination forms, and W-Mo ores usually occur in greisen or greisenized monzogranite. In conclusion, the genetic type of Jiagangxueshan W-Mo polymetallic deposit is greisen-type. Based on mineral assemblages and crosscutting relationships, the ore-forming stages may consist of an early silicate-oxide stage, followed by a sulfide stage. The microthermometric study of fluid inclusions shows that the W-Mo mineralization is relevant to ore-forming fluids at moderate to high temperature and low-middle salinity. From the silicate-oxide stage to sulfide stage, the temperature of the ore-forming fluids decreased obviously and the salinity decreased slightly as well.