The invention discloses a novel drill bit for high-precision internal threads and a using method thereof. The novel drill bit comprises a supporting rod inserted into the control end of a machine tool, and a cutter used for forming the high-precision internal threads is arranged on the side, away from the control end of the machine tool, of the supporting rod; the cutter comprises a side wall cutting edge arranged on the side, away from the machine tool control end, of the supporting rod, a plurality of side face milling cutting edges are formed around the side wall cutting edge at equal intervals, an end face milling cutter is arranged on the side, away from the supporting rod, of the side wall cutting edge, and a plurality of end face milling cutting edges are formed in the surface of the end face milling cutter. A combined end face milling cutter and a side wall cutting edge are creatively combined, the novel milling cutter rotates in the radial direction to form cutting power, meanwhile, a machine tool controls radial feeding and radial track movement, the end face milling edge is used for machining a hole in the surface of a workpiece in the radial feeding process, and the side wall single milling edge is optimally increased to be two or more. The milling resistance of each single blade is reduced; one-time machining of the threads is achieved through combination of the two methods, and efficiency is improved by more than one time.