This paper demonstrates that in karst areas, when either reflection wave or lateral wave on interface between ground (limestone) and air is negligible, and when either of these two waves, together with the direct wave in limestone, forms interference curve characterized by apparent extrema, the relative dielectric constant and phase constant of limestone are obtainable and, through dissolution of interference curve, amplitude of direct wave can be evaluated which, in turn, can lead to the determination of apparent absorption coefficient and apparent resistance. The corresponding approximate calculation is given, whose feasibility and precision have been affirmed by theoretical model and digit inversion of surveyed curves in fields of karst areas.These results also apply to other areas of low-dissipation media.