Abstract：Located in southeastern Da Hinggan Ling Yanshannian metallogenic belt, the Sandaowanzi gold deposit is a quartz vein type gold deposit. Based on geological characteristics, mineral features, ore-forming periods, fluid inclusions and S, H, O isotope compositions, the authors have reached the following conclusions： calaverite is the main gold mineral; δ34S values of pyrite range from －1.1‰ to 1.7‰，showing isotopic characteristics of mantle-derived sulfur; δ18O values of ore-forming fluids responsible for the formation of quartz are in the range of 15.3‰～－9.9‰, δD V-SMOW values of inclusion fluids of the quartz vary between －110‰ and－85‰; meteoric water is dominated; the homogenization temperatures are from 181 to 267℃, and salinities from 15.6% to 16.9% (Nacl eqv.); the ore-forming pressure is 4 Mpa; and the ore-forming depth is around 0.4km. The Sandaowanzi gold deposit is hence a mesothermal－epithermal gold deposit.