Abstract: The measurement of soil electrical conductivity has been increasingly gaining attentions because precision farming technologies rely on accurate field maps of the soil characteristics that affect field. In this paper, a mathematical model for four-electrode measurement method was developed. The discussion concerned with the model consists of three steps. At first, the behavior of single current electrode at a depth of field was treated. Secondly, a combination of two current electrodes at a depth of field was analyzed and some formulas used for different configurations of electrodes were developed. At last, a lemma associated with this model was proven. In addition, some experiment results and a general conclusion referring to this study were presented.