According to the basic theory of rock mechanics, fluid mechanics in porous medium, geologic mechanics, calculated mechanics and fluid-solid coupling seepage, a mathematical and numerical model of seepage field and stress field coupling is developed in porous medium and a computer program is designed with the method of finite element technique. The Coupling Law of depressurizing exploitation Seepage field /Stress field in porous medium is studied. By the method of numerical simulation the variation law of stress-strain with time and space around borehole of impermeable rock medium, variety law of rock physical properties parameters is studied. It can be seen from result that development and deformation of borehole elastic area mainly affected by ambiequal ground stress value, difference of ambiequal ground stress and rock material properties so on. But for the nonlinear rock medium, material plastic deformation is a key mechanics parameter closely related to distribution patterns of borehole stress. Therefore, based on rock mechanics experiment，it is necessary to further consider influence of plastic deformation mechanism to the stability of the borehole.