Calcite is one of the main gangue minerals in the Zoige Uranium Ore Field, which has a most close relation with uranium mineralization. Based on analyzing geochemistry characteristics of REE of calcite in strata, calcite in the mine area and ore-bearing calcite, their REE model is characterized by enrichment in light REE (decline to right), heavy REE (decline to left) and relatively flat of REE distribution patterns, respectively. Among them, calcite in strata shows the characteristics of the obvious inheritance of the sedimentary rocks, while the characteristics of rare earth elements of the ore-bearing calcite are similar to those of the ore-stone. Carbonoxygen isotopic characteristics of calcite in strata shows the carbon-oxygen compositions of marine carbonate rocks, while the other two implying an involvement of mantle derived source. Oxygen isotopic characteristics suggests existence of deeply-derived fluid for the calcite in the mine area, while oxygen isotopic characteristics of ore-bearing calcite show the evident addition of some introduced fluids possibly from infiltrating atmospheric water into the ore-forming fluids. Calcite in Zoige Uranium Ore Field is mainly of hydrothermal origin, and the type of the genesis is a typical hydrothermal deposit with its ore forming fluid originated from mantle.