Impact compactor is a compaction machinery with high impact energy,which cracks the old cement concrete pavement to form a interlocking structure and be the cushion or sub-base of the new pavement.Combined with the S249 Pingru provincial road innovation project,this paper gives a brief introduction about the working principle of impact compactor,the construction technology of impact compaction,makes typical analyses on the effect of the settlement,and puts forward the existing problems of detection methods of impact compaction. Key words:impact compaction;construction technology;settlement analysis;fracture block size