This paper describes in detail the process of numerical modeling forthe apparent resistivity (in direct current domain) to 3-dimensional underground geological bodies according to the boundary integral equation and the spatial locations of the bodies. Based on previous theoretical basis and progressive modification in some aspects, the authors modeled and examined the response to several different kinds of sounding devices. As a result, some principles concerning the locations of underground electrical bodies and the corresponding relationship between the geometric parameters of underground objective bodies and the types of characteristics of apparent resistivity anomalies were obtained.