The Qilishan gold deposit is located in the southern Zhaolai gold ore belt in the northwestern Jiaodong region． A total of seven gold ore bodies have been found in the mining area． Linglong gneissic biotite granite and the NE trending Lingbei fracture control the output and distribution of the gold deposit． The ore bodies with veined or irregular shape occur in the structural alteration zone． The ore bodies of different sizes are NE trending and SE dipping． The constituent minerals of the ores mainly include pyrite，chalcopyrite，native gold，electrum，argentite，matildite，hematite，quartz and calcite． The ores are characterized by metasomatic dissolution structure，as well as veined and brecciated structures． The ore-forming process is divided into four stages，namely quartz-，pyrite-，polymetallic-and carbonate stages． Study on fluid inclusion shows that the deposit is composed of gas-liquid two-phase inclusions ( I) and three-phase inclusions containing CO₂ ( II) ，and that the former dominates． The homogenization temperature is 259. 6℃--373. 7℃; the salinity of three-phase inclusions containing CO₂ is 5. 77%--9. 84% ( NaCl) ; the salinity of gas-liquid two-phase inclusions is 6. 58%-- 8. 54% ( NaCl) ; and the estimated ore-forming pressure is 55. 2--82. 2 MPa. According to the nonlinear relationship between the depth and pressure of the fluid in the fracture zone，the ore-forming depth of the Qilishan gold deposit is calculated as 5. 95--7. 14 km． It is preliminarily determined that the deposit is a mesophilic and hypothermal gold deposit．