Abstract: Based on the data of chemical analyses of the fractured rocks within cross sections of a few tens of fault zones in eastern China, there are obviously successive change pattern for the content of element Si, and from various different presents including the metamorphism, component composition, micro-structure, zonal differentiation, and tectonic background etc., the tectonogeochemical behaviour of the element Si can be divided into a low grade metamorphism type (abbreviated as L type) and a very low grade metamorphism type(VL type). In the former, the metamorphic temperature is more than 200-250℃, and the metamorphic facies matches with the greenschist. But in the latter, the metamorphic temperature is less than 200℃, which coincides the zeolite metamorphic facies. As a matter of fact the complex change of element Si in fault zones is closely corresponding to fieldspars in practical examples. Obviously multi-period features of the dynamic differentiation can result in the multi-times of metamorphic differentiation and chemical differentiation.Thus many kinds of dynamic metamorphic equilibrium systems of the element Si could be formed such as SiO2-K2O-Al2O3-MgO-MnO and so on. Finally the significance of the discussion mentioned above to the geological research of resources and environment has been briefly described. On the one hand, most of mylonites hosting gold ores are some siliceous mylonites, and they were distributed in many provinces in the eastern area of China. On the other hand, the silicified rock can weld fault zone to prevent the sliding slope, and these phenomena are often discovered in the Lower Yangtzi area.