Abstract: The effects of changes of stresses on the hydraulic conductivity in fractured rock masses are studied.The fractured medium is approximated as an equivalent fracture network in which a single fracture is idealized as a planar opening having a constant equivalent aperture, changes in fracture aperture due to the changes of stresses control a change of hydraulic conductivity.Some models are presented to study the relationship between stresses and hydraulic conductivity.Experimental results are given to illustrate that hydraulic conductivity and water flow depend upon the applied stresses strongly.Through the finite element model and using formulas given in this paper the changes of hydraulic conductivity in a mining face are examined.