Abstract: One of the defficult problem for boundary element method is to deal with the singularity of foundamental solution. In this paper, the singular foundamental solution is avoided and a boundary integral equation is set up by applying non-singular foundamental solution. The nonsingular foundamental solution is obtained from the general solution and complete system of homogeneous differential equation and the solution of the boundary integral equation becomes easier. Spline interpolation used for boundary unknown quantity makes the calculation in good precision.