Abstract: The fluid activities of the Baolun gold deposit were characterized by several phases.In this study,the compositions,salinities and homogenization temperatures of the fluid inclusions in the quartz veins formed in each phases are different,based on microscopic temperature measurements of fluid inclusions.In the gold-bearing coarse-grained quartz veins formed during Phase I;in the gold-bearing fine-grained quartz veins formed duing Phase II;in the gold-bearing multi-metal sulfide quartz veins formed in Phase III.Generally,the temperatures of the fluid gradually increased,and the salinities decreased.Combined with the laser Laman analyses and previous O isotopic studies of other researchers,we consider that the ore-forming fluids were high temperature immiscible hydrotherm of magmatic hydrotherm produced by the Jianfengling Magmatism and meteoric water.The ore-forming hydrothem went up along the fissures,resulting in ebullition as the pressure released,and continuously mixed with the meteoric water,which changed physical and chemical properties of the fluid.This finally conduced to the precipitation of gold.