1. Heilongjiang Institute of Geological Survey, Harbin 150036, China;
2. College of Earth Sciences, Jilin University, Changchun 130061, China

Yingchengzi gold deposit is a typical epithermal deposit. To understand the mineralization condition of the deposit, integrating the geological characteristics of the deposit, the authors undertook microthermometry and laser-raman spectrum analysis on the fluid inclusions from the same gold-bearing quartz vein of different depths. The results show that the ore of Yingchengzi gold deposit is mostly alterated rock type, and the rest is quartz vein type. The mineralization processes can be devided into four phases:(I) Quartz-arsenopyrite-pyrite phase, (��) Quartz-pyrite phase, (��) Quartz-polymetallic sulfide phase and (IV) Quartz-sulfide phase. The fluid inclusions are mainly in gas-liquid phase,with the rest in single phrase of gas or liquid or in three phases. The homogenization temperature ranges from 247.9��~400��, salinity (w(NaCl)) ranges from 3.15%~7.70%, and the mineralization fluid density is 0.65 g/cm³~0.87 g/cm³. Combined with the data from inclusions laser-raman spectrum it is concluded that ore-forming fluid belongs to a medium to low temperature, medium to low salinity CO₂-H₂O-NaCl system. According to the results of thermometry, the pressure of ore-forming is 6~50 MPa, at depth of 0.11~0.65 km. Therefore it is concluded that the deposit is a medium temperature, medium pressure hydrothermal gold deposit related to ductile deformation. Combing the previous studies of metallogenic chronology, it is confirmed that the mineralization occured during the Asian oceanic crust subduction of Late Permian, and was related to the transformation of tectonic regime during continental collision of Songnen Massif and Jiamusi Massif.