To carry out the construction of cast-in-place pile foundation under the geological condition of large rock backfill of the approach dike，we adopt the construction technology of slurry wall punching cast-in-place pile. In the course of drilling，some construction measures are taken，such as increasing the diameter of the hole to rectify the deviation，increasing the thickness of the casing to prevent the extrusion of the hole，increasing the length of the casing and filling the hole with concrete to stop up the leakage，increasing the diameter of the hammer and weight of the punching hammer to penetrate the boulder，etc. ，by which the quality of hole-forming is guaranteed，and the experience of hole-forming construction of cast-in-place pile under special geological conditions is accumulated，serving as reference of similar projects.