Abstract: Combined with the polished section and thin section of ore minerals and gangue minerals under the polarizing microscope，and adopt the field geology and drilling core sampling methods，the charac⁃ teristics of the ore minerals in Tin (Tungsten) Polymetallic Deposit in Xiwukou mining area is summarized， and four alteration zones are divided as silicification，angle lithization，greisenization and muscovitization. According to the mineral assemblage，mineral paragenetic sequence，metasomatism relationship，metamor⁃ phic degree，the analysis indicated that the orebody is mainly distributed in greisenization and muscovitiza⁃ tion zone.The study results show that the deposit is the typical magmatic period after pneumato-hydrother⁃ mal deposit，namely high temperature gas topaz quartz vein tungsten tin deposit，accompanied by copper， molybdenum，bismuth，beryllium polymetallic deposits，metallogenic form are high temperature quartz vein tungsten ore，tungsten tin and granoxite series composite deposits.

Key words: tin (tungsten) polymetallic deposit, polarizing microscope, mineral identification, polished sectiont and thin section, mineral assemblage, mineral paragenetic sequence