This paper uses the sericite phyllite and siliceous plate phyllite of Middle Devonian series on upriver of Jinsha River as the research object. The micro-rupture properties of rock are judged and the relation between the form and mechanism of phyllite micro-rupture and mineral component is revealed through scanning electronic microscope and mechanical tests. The sericite phyllite shows micro-scratch micro-fracture fracture which is a typical micro-brittle shear. The physical meaning of rock fracture is analyzed with the combination of mechanic characteristics of macroscopic fracture. The evidence is acquired to establish the link between rock micro-rupture mechanism and macroscopic fracture analysis.