Abstract: Interactions between microorganisms and minerals take place widely on the Earth，which lead to dissolution or precipitation of minerals and thus play an important role in the natural environment and economic development．The study of mineral weathering by microorganisms involves many fields and disciplines． Furthermore，weathering of minerals is related to the formation and evolution of soil，development of vegetation and formation of mineral deposits．This paper focuses on mineral weathering by silicate bacteria．Potassium feldspar，illite and other common minerals were selected for this study．These minerals were incubated in nitrogen—free medium containing bacteria．During incubation samples were collected from the culture and analyzed using X—ray diffraction and electron microscope．The results showed that the bacteria indeed eroded the surface of the testing minerals，which were characteristic of round shapes and uneven surface．The mineral particles were covered with numerous bacteria．Furthermore．bacteria selectively degraded different minerals due to difference in mineral crystal structure．In the absence of bacteria，minerals remained intact，which were characterized by sharp edges and corners．The mechanisms of mineral weathering by silicate bacteria were also discussed．