The six groups of fault gouge samples were collected in different middle-sections from the underground mine of the Weilasituo zinc-copper polymetallic deposit, Inner Mongolia. The samples were analyzed with X-ray diffraction (XRD) and near infrared spectrum (NIR)to explore the mineral composition features of the fault gouges and their relationship with mineralization. The results are as follows: (1) The fault gouge samples contain the clay minerals which were formed in the low temperature alteration (such as montmorillonite, kaolinite, dickite, chlorite etc.), the alteration minerals in the medium temperature or high temperature hydrothermal environment (such as graphite, black mica, pyrophyllite, barite, serpentine, tremolite, actinolite etc.), and also the mineral compositions which were closely related to mineralization (such as copper-zinc oxide, copper-vanadium-chloride, azurite, bornite etc.). (2) The mineral compositions of the fault gouge from different depth are different. Shallow earth's surface is mainly consisted of the low metamorphic minerals, and deep underground is mainly consisted of the high metamorphic minerals. (3) The mineral composition, mineral genesis and law of development of evolution of fault gouges suggest that, they were formed in the ore and metallogenic tectonic hydrothermal activity period, and had experienced the supergene oxidation later. (4) Through the analysis of the mineral compositions and alteration mineral assemblage characteristics of the fault gouges we can speculate that, the ore deposit was formed in medium-high temperature hydrothermal environment which had experienced the process of silicide, kaolinite, chloritization, hotaru petrochemical and sericitization alteration. Therefore, the analysis of the mineral compositions and mineral assemblage characteristics of the fault gouges,not only have certain practical significance for prospecting, but also can provide important reference information to study the genesis of the deposit.