Based on the relationship between the diameter and buried depth of goaf，the authors establish the forward modeling by Res2dmod and inverse the model by Res2dinv． Thus，three kinds of models are obtained: the model of single resistivity anomalous body，model of double different distance resistivity anomalous body， and model of layered resistivity anomalous body． Using forward and inversion，the image of detection is simulated， and the reliability is proved by comparing with the engineering examples．