The Hashan area in the NW margin of the Junggar Basin experienced multiple phases of intense tectonic movements, with fissures well developed in Carboniferous and Permian systems and most filled with calcite. This study discussed formation fluid activity and its relationship with hydrocarbon accumulation using analyzing the geochemical features of carbon, oxygen and strontium isotopes, and fluid inclusion of fillings from calcite veins. The results indicate that calcite fillings are generally influenced by both volcanic hydrothermal fluid and oil source fluids. δ13C feature reflects that mantle and atmosphere were two sources for the carbon elements in calcite, and negative characteristics of δ18O mainly reflects the influence of high temperature fluid medium, and the ratios of 87Sr/86Sr means that it was affected by both the mantlederived strontium and crustderived strontium. Comprehensive analysis suggests that there were three genetic mechanisms for formation of calcite veins: volcanic hydrothermal, petroleumderived fluid, and meteoric water, each of which corresponded to Carboniferous and Permian volcanic hydrothermal fluid activity, oilsourced fluid since late Permian, and meteoric water in late period. The homogenization temperatures of the secondary hydrocarbonbearing brine inclusions developed in calcite fillings are distributed in three temperature ranges: 70~80℃, 100~110℃ and 130~160℃, corresponding to three phases (Late Permian, Late Triassic, Late Cretaceous) of oilsource fluid charging, respectively. Among them, the Permian oilsourced fluid made important contribution to Carboniferous and Permian hydrocarbon accumulation.