Abstract: According to the very important role of the horizon data (or the seam reflection time) in the structure explanation process of the 3D seismic exploration in the mining block, in order to fully excavate the useful information in the seismic exploration horizon data and to more accurately explain the fault and other geological st ructure, taking the 3D seismic data of a mining block in Xinglongzhuang Mine as the basis, the self prepared software was applied to pick up the horizon data of No.3 s eam, the gradient was calculated with the numerical method, the explanation drawings were prepared and secondary explanation of the structure was conducted.The ap plication results showed that the method could clearly expand the fault, the explanation of the large fault would not be omitted.Thus the accuracy and reliability of the fa ult explanation could be improved.