Abstract: The Jiefangyingzi gold deposit is located in the continental margin accretion zone in the northern part of the North China plate. The ore body is veined in the Middle Silurian Shaiwusu Formation, and the mineralization type is mainly quartz vein type. In order to confirm the ore-forming fluid characteristics, ore-forming material sources and ore genesis, fluid inclusions, H-O-S isotopes and sphalerite trace elements were tested and analyzed. The results show that the ore-forming fluid in the early ore-forming stage belongs to the CO₂-H₂O-NaCl system hydrothermal fluid with medium temperature, medium salinity and low density. The ore-forming fluid in the main ore-forming stage basically continues the characteristics of the I ore-forming stage. The ore-forming fluid belongs to the H₂O-NaCl system hydrothermal fluid with medium-low temperature, medium-low salinity and low density. The results of fluid inclusion temperature measurement and isotope show that the ore-forming fluid is mainly derived from magmatic hydrothermal fluid, and the decrease of fluid temperature and the addition and mixing of meteoric water in the main metallogenic period may be an important mechanism of gold precipitation mineralization. The sulfur isotope results show that the sulfur source of the ore is close to the sulfur isotope value of the mantle, indicating that the ore-forming material is derived from magmatic rocks. The results of trace elements in sphalerite show that the Jiefangyingzi gold deposit was formed in medium temperature hydrothermal condition, and the genetic type of the deposit belongs to magmatic hydrothermal type. Comprehensive analysis shows that Jiefangyingzi gold deposit is a medium temperature hydrothermal vein type deposit.