When detecting the underground cavity by the high density resistivity method, a deviation detection results were made due to the interference factor of the type of underground cavity and current distribution. Typical models of underground cavity were simulated and analyzed by means of numerical simulation method of ANSYS. The results show that the accuracy of the detection results not only involve with the depth, the level of resistivity values and the distance of the adjacent hole, but also has something to do with the type of detecting devices and the electrode spacing etc. Through the numerical simulation of high density resistivity method in the actual coal mining area, the calculation results and the field test results are basically consistent. And it also proves that combining the numerical simulation results and the field test results have good reference value for supplementary explaining and accurately determining the distribution of underground cavity.