The volume integration of potential function in the graund can be transformed to the integal equations of the potential function on the surface by using the Green's formulas and the boundary conditions of a point source. The boundary elements methods used to solve the integal equations and the potentials on topography are therefor obtained. The precision and the speed of the calculation are determined by the dividing method and the density of the poinrs. In this paper, use is being made of a method of divid...