The invention provides a dresser for a deep hole internal thread and belongs to the technical field of hand tools. The dresser comprises a locating mandrel, a ferrule, a threaded cutter, a fixing seat, a fixing sleeve and a baffle, wherein the locating mandrel penetrates into an inner cavity of the fixing seat, and a tapered surface is arranged at the lower end of the locating mandrel; the ferrule is embedded into the inner cavity of the fixing seat; the threaded cutter comprises four groups of L-shaped blades, a cutting edge with a thread form consistent with that of the deep hole internal thread of a to-be-dressed aircraft part is arranged at the outer side end of the horizontal arm of each blade, a wedge-shaped arc surface is arranged on the vertical arm of the blade, the four groups of blades are evenly arranged around the locating mandrel, and the horizontal arms of the four groups of blades are assembled with the fixing seat; an operating handle is arranged at the upper end of the fixing seat, the fixing seat and the fixing sleeve are assembled in a threaded fit manner, the thread pitches of the fixing sleeve, the fixing seat and the deep hole internal thread of the to-be-dressed aircraft part are identical, and the fixing sleeve and the to-be-dressed aircraft part are assembled in a threaded fit manner. The dresser solves the problem about repair of the deep hole internal thread of the aircraft part and guarantees smooth assembly of threaded fit members in the maintenance process of the aircraft.