Drill rod connecting drill tail

The invention discloses a drill rod connecting drill tail. The drill rod connecting drill tail comprises a tail rod, a gear seat, a through hole and a second butt joint groove, wherein a threaded connecting end is arranged on the outer side of one end of the tail rod; a limiting ring is arranged on one side, close to the threaded connecting end, of the tail rod; the gear seat is arranged at one end, far away from the threaded connecting end, of the tail rod; a connecting hole is formed in the middle of the tail rod in a penetrating mode; the through hole is formed in the tail rod; a first buttjoint groove is formed in one end of the through hole; and the second butt joint groove is formed in the through hole at one end far away from the first butt joint groove. According to the drill rodconnecting drill tail, the drill tail of the drill rod is in threaded connection with an internal threaded pipe sleeve of the drill rod through the threaded connecting end on one side of the tail rod,and meanwhile, the connect