Abstract: On the basis of systematical observation on mylonites in hundred of fault zones or more in eastern China and with referring to different divisional views of some researchers for mylonites categories,authors have stressed such three factors on which classification of mylonites depends as the texture,the mechanical genesis and the physical character of fault rocks.Obviously,mylonites which may be included in ductile deformation are based upon the characters of physics and mechanics.Actually,these mylonites may be also divided into three categories,shallow,low temperature and brittle deformation mylonite,i.e.B type;moderate-high temperature and ductile mylonite,i.e.D type;deep,high temperature viscous mylonite i.e.V type.As mentioned above,each category of the mylonite shows the different typical character.B type (brittle-tracture type) is of mylonitic texture,the D type (ductile-gliding type),of subgrain structure,and the V Type (viscous-flow type),of flow structure.These properties are correlative and may have a transition each other as well.In the studied categories,authors mainly describe and compare the B and D types of the mylonite.