Based on scanning electronic microscopic observation of three fault rocks in ductile-brittle shearing-sliding zones (including one palimpsest mylonite sampled from deep bore cores of Cajon Pass, California, two flowing-structured carbargillites sampled from Shaancan Well 1 located in north Shaanxi, and Well NH located in Huanghai, respectively), micron- and nanometer-scaled ultra-fine grinding grain texture of fault rocks is discovered in this study. And the geological significance of grinding grain texture is discussed in terms of its particulate organization, rheology of particulate slipping, laminar petrography and micro dynamics including dynamothermal metamorphism, fluid transferring, particulate autorotation, and so on. In addition, the remaining problems to be solved and broad prospects in this new study field are also discussed.