By the exploration of pile foundation construction method of rotary drilling rig under the combination conditions of strong seepage and hard rock bed, the combined drilling method of anti-seepage is summed up and has been successfully applied in the engineering, which is by high pressure jet grouting with cross use of cone tubular drilling and pick coring tubular drilling of rotary drilling rig to break into rocks. Obvious effects have been received in the construction of large diameter bored grouting pile in hard rock bed.