Abstract: in this paper, the boundary integral equations are proposed, in which the field point and the load point are separate. The results of error analysis prove that the precision of numerical calculation is affected mainly by the coefficient error and the determinant value of BEM system equation. Through an analysis showing that the distance between the field point and the load point can affect the coefficient and the determinant value mani festly, useful results can be drawn revealing that the precision of calculation through regular BEM is much higher than that of singular BEM and that numerical stability of indirect BEM is better than that of direct BEM. The analysis can qualitively explain the results of numerical calculation given in this pape r.