The present paper Prerrpb the leastt square method for calcdating fijiecoefficient of symmetrical quadiupole electrical sounding,with the forward filtercoefficientS given when two sets of ecentrlclty(MN/AB) are and I/Srespectively. Sampling Intervals are 0.6.IN all, there are 15 coefficients In theformer case and 13 coefficients In the latter case.The precision of the filterand the necessity of taking into account the polar distance for measllrelncnt arealso dealt wvth in this paper.