Studies on the characteristics of fluid inclusions show that the fluids that were responsible for the formation of gold-poor quartz veins of early metallogenic stage in the minging district are medium temperature, low salinity and CO2 and CH4-rich solutions. Comprehensive analyses revealed that the fluids of the early metallogenic stage maily derived from the Sanguliu granodiorite of late Yanshanian epoch; the fluids forming the major metallogenic stage might be related with subsequent granite porphry dykes and the fluids that were responsible for the later metallogenic stage mainly came from meteoric water. The conclusion was made that the Sidaogou gold deposit was the result of the superimposed mineralization of different sourced fluids with different characteristics.