Because of the complex composition, loose soil layers and low mechanical strength in miscellaneous fill site, pile foundation construction is difficult, especially for where being newly filled. With a case of bored cast-in-place pile constructed in miscellaneous fill of Changbai Mountain area, the impact drilling technology is selected after the analysis on the applicability of different holing methods. This paper introduces the construction process, difficulties and countermeasures as well as mud treatment, expounds the construction technology of rock-socketed piles in thick-layer miscellaneous fill site.