Abstract: Guocheng Gold Deposit is located on the northeast margin of Jiaolai Basin.It is composed of Tudui ore section,Shawang ore section,Dongliujia ore section,Longkou ore section,and Houkuang ore section.It is controlled by the detachment structural system dominated by Guocheng fault.The petrography and microscopic temperature measurement of quartz fluid inclusions in the ore show that the fluid inclusions in the deposit can be divided into 3 types:gas-liquid two-phase inclusions,CO2-containing three-phase inclusions,and pure liquid phase inclusions.The salinity of ore-forming fluid is 1.39 %-16.53 %,and the density is 0.56-1.00 g/cm3.It belongs to medium-low salinity and low-density fluid.The ore-forming temperature is 200 ℃-360 ℃,and the pressure of ore-forming fluid is 60-125 MPa.The ore-forming depth is 6.22-9.31 km.Based on predecessors-research achievements,it is considered that the genesis of Guocheng Gold Deposit is a mesothermal hydrothermal vein type deposit,of which the mineralization involves mantle fluid,controlled by the detachment structural system dominated by Guocheng fault.