The large-diameter ultra-deep high-pressure jet grouting pile construction technology in hydrodynamic sand bearing layer is one of the difficult problems in the current jet grouting method. Its main difficulties include the cutting and slurry retaining problems of sand layer. The aspect of insufficient cutting force is that the soil is more tightly consolidated, and the other is the insufficient jetting force. The slurry cannot be stored retained because the groundwater flows under the influence of tides. The initial setting time of cement slurry is also longer and the groundwater flow takes away the cement slurry. The above two problems are targeted to study. The measures of double-pump grouting, increasing jet nozzle and pre-cutting bentonite slurry to be taken can have the obvious effects in the guarantee of finished pile diameter and the increase of slurry retaining amount.