In order to improve the accuracy of advanced detection of water disaster and structural anomaly in coal mine roadway,three boreholes for advanced water detection are used. These three boreholes are designed as “triangular cone” with 28 degrees each other,and three dimensional direct current method in the holes of “triangular cone” observation system is used for the advanced detection of water inrush disaster. Under the condition of a homogeneous full space and layered model,the forward modeling models of bulk low resistance anomaly and plate low resistance anomaly are designed,and the response characteristics of the low resistance anomaly are compared with those of the traditional DC method. The results are as follows:① Under the homogeneous model,the response of the traditional direct current method of advanced observation system to the body shaped and plate shaped low resistance anomalies is almost the same. However,in the layered model,the response of “triangular cone” type observation system to the body shaped anomaly is dozens of times larger than that of traditional advanced detection system. The response of “triangular cone” type observation system to the plate shaped anomaly is several times larger than that of the body shaped anomaly. ② The response of “triangular cone” type observation system to anomaly is stronger than that of traditional advanced observation system,and the response to low resistance model is dozens or even hundreds of times larger than that of traditional advanced observation system,which is more conducive to the acquisition of anomaly signals. ③ Since the electrodes are arranged in the holes,the “triangular cone” type observation system greatly reduces the interference of various human factors in the roadway to the signal,avoids the problems existing in the traditional DC method of advanced detection,and is a new solution for advanced detection. The simple geologic anomaly body under a homogeneous model can be located by the arc intersection method,while the spatial accurate location of the complex model needs to be solved by three dimensional resistivity inversion.