Abstract: In order to overcome the inconvenient power supply in the mine roadway during the electric advance geological prediction and the complicated problems of the data explanation, a long pole span fixed power site building mode with a power supply from the surface ground was provided.With the measurement of the potenti al difference near the coal mining face and the abnormal of excitation polarization, hidden dangers were judged. The physical simulation experiments showed that when the low resistances sphere hidden danger was reached closely, the potential difference would be increased obviously, abnormal of the polarization rate would be a nega tive value and would be reduced continuously.The 3D observation system measurement was applied to realize the real time early warning of the hidden danger.With the comparison analysis on the abnormal in each direction, the space location of the hidden danger could be determined.The prediction method applied to the advance pre diction of the hidden danger in the underground excavation project could have a certain distinguishing ability of the abnormal mass in front or near the working face.