The dipole device has small electromagnetic coupling, and is a common device for amplitude-frequency induced polarization. Dipole quasi-cross section contains abundant information, and is therefore beneficial to raising inference level. Nevertheless, the insufficient research has affected giving full play to its role. For the purpose of solving this problem, we have made a systematic study on characteristics, laws and inference method of dipole anomalies. The basic results obtained are reported ill this paper, i. c. , the graph-source cor responding law of single-source quasi-cross section under the condition of horizontal topography.On the basis of describing and defining graphic characteristics of quasi-cross section, this paper gives the corresponding law between graph-source local characteristics of a set of low-tesistance sources under the condition of two-dimensional linear source and the corresponding law between the overall characteristics of a set of common graphs-sources. The former includes the corresponding law between upper, middle, lower characteristic points and up per, middle characteristic lines, whereas the latter includes saddle-peak law, valley distribution law, variation law of isostatic value, orthogonal law and symmetry corresponding law. .Finally, using model experimentation and mime rical calculation, the paper proves that the above laws arc also suitable for three-dimensional point source condition.