The relationship between thermal conductivity of geotechnical material and its porosity is simulated by using finite element method. The solid matrix and pore are generated randomly according to material porosity

and material parameters and element properties are changed by ANSYS parameter design language. The effective thermal conductivity is computed according to thermal flux through some section computed by FEM and Fourier heat transform low. The investigation shows that the effective thermal conductivity decreases with increasing porosity

and the gradient increment of effective thermal conductivity with respect to porosity ratio may decrease obviously while the porosity reaches percolation critical value

and the thermal conductivity characteristics of geotechnical materials pose the percolation transform properties that are the same as seepage in porous medium.