Abstract: To achieve an advanced detection in coal mine roadway,a method called focusing dual-frequency induced polarization method based on dual-frequency induced polarization method and electric field scanning detection theory was proposed in this paper. Based on the theory of collinear point current source electric line equation,the detection electric field boundary electric line equations were established and the complete algorithm was derived. The electric field scanning detection strategy was proposed and the actual resolution of electric field scanning detection was ana- lyzed with the boundary electric line equation. Based on dielectric boundary conditions theory,the offset vector of the electric line was derived according to the roadway geological structure model,and the influence of geological anomaly on the electric line was analyzed. Theoretical calculations show that the detection electric field scanning resolution can be set arbitrarily by continuously changing the current amplitude of different channel of the detector theoretically,but it is set according to actual detection conditions. The existence of geological anomalies will affect the distribution of elec- tric line and the greater of a,ρ1 / ρ2 and β( β≥90° -α),the larger the absolute value of the offset vector of electric line. The size and orientation of the geological anomalies could be calculated through electric field deflection and focu- sing canning detection.