The long spiral CFG pile construction often causes crack while in saturated slit. 3D finite element model is carried out, and the deformation of drilling hole is analyzed. The deformation’s factors are emphtically discussed such as drilling depth, dumped-soil load, soil strength, groundwater level etc. The results show that uneven settlement and horizontal displacement are relatively small while silt has high strength. The reduced soil strength is the main factor of drilling holes’ deformation, which causes serious hole shrinkage and the soil is brought to surface with spiral blade, and then causes “excessive dumping” and soil cracking.