Abstract: Mylonite bears rich information of geological processes and is of great importance not only in the theoretic study but also in the geological practice. In this paper, the authors will review the progresses of mylonite petrology in the past two decades based on studies of micro-ultramicroscopic structure, solid state rheology, mineralization of dynamic metamorphism, modeling experiment of rock formation, tectono-gecchemistry, orogenic kinematics and isotopic chronology. Some new results of mylonite study, are discussed, which include discovery of mylonite in the shallow level, experiment of rock formation for the artificial mylonite and new data of chronological dating, etc., We also suggest that microscopic research of mylonite could be further extended into the new fields in studies of crust-mantle theology, tectono-chronology and the comparative geology of orogenetic belts. Fina1ly, it should be shown that some concerning laws of the physics (such as the Helmholty law) will be cited for the mylonite research in the microscopic scale, thus the dislocation forming rule and the mechanism of rock rheology could be completely interpreted. Moreover some results and models (example S-C foliation type) are also applied on a delineation deformation research, in particular, the discovery of the mylonite in the shallow level has helped to bring new discussion of the seismic rupturing genesis. The various rich informations in mylonites will be explored out through the parameters determinated by the rock mechanics, tectono-physics, geochemistry and rheology, further the new coupling mechanism of the geological action could he revealed in more detail.