Abstract:Big difference between the hypothetic condition of horizontal layered uniform medium that the P-wave reflections multiple coverage method based on and practical situation is main reason affecting the imaging of mountainous seismic data and resulting in failure of exploration.In view of the issues appearing in imaging of mountainous seismic data,the paper analyzed the influence of lateral velocity variation on seismic imaging by simple model computation,which is shown as non-symmetric relevant ray paths on both sides of CMP and CRP or dispersion of CRPs.The paper questioned on practice using ultra-long seismic spread for surveying and selecting spread segment for stack in complex mountains and presented the issues needing attention in seismic acquisition and processing works in complex mountainous foreland area under current technical conditions.