The invention discloses an underground
coal mine large-
diameter directional drilling system and a hole forming method. The
system comprises a directional
drill bit, a single-bend screw motor, a non-magnetic drilling tool, a packing cross short section, a double-wall drilling rod and a double-channel water injection and
slag discharge device which are connected in sequence, and a mud
pulse measurement-while-drilling instrument is arranged in the non-magnetic drilling tool; the packing crossed short section comprises a short section body and a limiting connector which are connected, and the outer wall of the short section body is sleeved with a sliding sleeve. A double-wall
drill rod local reverse circulation mode is adopted for deslagging, compared with a conventional direct circulation mode, the circulating water amount needed for deslagging is greatly reduced, the
water supply and
pollution discharge requirements of a
directional drilling site are greatly reduced, the rated
discharge capacity and power of a matched
slurry pump are greatly reduced, circulating water flows in an annular channel and a center channel of the double-wall
drill rod, and the
water supply efficiency is greatly improved. The overflow section is not influenced by the hole wall stratum, the reverse circulation flow deslagging efficiency is high, the cleaning effect in the hole is good, and the technical problems that the amount of circulating flushing liquid needed by a conventional large-
diameter directional hole
drilling system is large, and the hole wall stability maintaining capacity is poor are solved.