According to the former formula and the experience,the influence to the seepage discharge and the seepage gradient when the cut-off wall's place be changed under the infinite deep pervious foundation were still not be clear.This paper makes use of the Boundary element character and the computational thereoy to abtain the formula model of sovling this problem and to establishes the corresponding computational procedure.The influence of the place and depth of cut-off wall to the seepage was also analyzed.The results can provide the reference for the next engineering design.