In order to understand the dynamic stress diffusion rule of the waste iron slag (sand soil) during dynamic consolidation, we conducted a large field test. The propagation and attenuation of dynamic stress in each ramming strike was recorded through the resistance strain gauge. It was shown that the dynamic stress caused by dynamic consolidation is pretty obvious. The dynamic stress dissipates extremely fast during the dynamic consolidation, the time is only 0.5s after plus the aftermath. The soil dynamic stress has heart-shaped distribution during the compaction. The dynamic stress value increases with the tamping hit number, but it keeps stable after about the third hits.