Abstract: Well Huo14 north fault block is located in north side of Shazhang bruchfalten zone in Eastern uplift of Junggar basin. The target interval is the Permian Pingdiquan formation, the main part is generally beneath the carboniferous volcanic overthrust nappe. Affected by the overlying unequal thickness volcanic high?speed zone, the Permian in this block is of characteristics of fast change of lateral interval velocity, developing interference wave and poor quality of seismic data. So the complex velocity changes restrict understanding of structural features within the block and technological breakthrough in oil?gas exploration in this area. In this paper, the volcanic rock body, its distribution and contact relationship are distinguished using the forward and inversion techniques of geological model, based on which by analyzing the waveform and attribute characteristics, the volcanic overthrust nappe structural shape and highs are defined. Meanwhile, using velocity?varied mapping technique improves the structural mapping accuracy