Located in the west of the Beishan metallogenic belt in Xinjiang, the Xiaochangshan iron deposit is hosted in gabbro and the contact zone of the gabbro and marble. Parts of the orebodies are hosted in the contact zone of the granodiorite and the marble. Previous researchers hold that the age of gabbro in the mining area is (276±1.2) Ma, similar to the age of gabbro in the Pobei copper-nickel-sulfide orebodies, so they both belong to Early Permian. The magma injection is an obvious phenomenon in the Xiaochangshan iron deposit. The orebodies occur as lenses, lumps, veins and thin layers. Metal minerals are mainly magnetite, with very little limonite and pyrite. The country rock alteration in the Xiaochangshan iron deposit is weak, comprising mainly garnetization, epidotization and marbleization. The electron microprobe analyses of magnetite show that the content of FeO_T in different iron ores has a large distribution range, and the content of Al₂O₃ is relatively higher. The ternary plot of TiO₂-Al₂O₃-(MgO+MnO) and TiO₂-Al₂O₃-MgO suggest that the formation of the Xiaochangshan iron deposit was associated with hydrothermal metasomatism of magmatic-hydrothermal fluid. The electron microprobe analyses of garnet show that the garnets from the Xiaochangshan iron deposit belong to andradite-grossular solid solution series, somewhat different fromthings of the typical skarn deposits. Combining the geological characteristics of the Xiaochangshan iron deposit with the study of the electron microprobe analyses, the authors believe that the Xiaochangshan iron deposit belongs to the polygenetic and compound deposit with magnetic and hydrothermal genesis, with the latter factor probably playing the major role.