Abstract: The coal deformation,density and fluid penetrating regularity in multi-fractures are the key problems in gas-rich coal development.The mechanical media properties,micro-structural model,permeability,and fractal characteristics of porous cracks and fragmentation of gas-rich coal-rocks are discussed.Electro-hydraulic servo tests of complete stress-strain process of coal samples are conducted by using the electro-hydraulic servo controlled rock mechanics testing system and the numerically controlled transient permeability method.The varying charac-teristics of coal sample permeability are studied.The tests reveal that the mechanical properties of coal are related to micro-structure,micro-porosity property,and the permeability is related to fractures variation.