Abstract: In order to discuss the relation between stressstrain and permeability of rocks,with the Electro-Hydraulic Servo Controlled Mechanics Rock Testing System of American MTS Corporation(815.02),adopting instantaneous permeating method,the permeation coefficient variety of sandstone under the coal floor in the process of mining is simulated.The results show that the coefficient of permeation is not only related to stress status,but also to rocks' structure and properties.