The utility model provides a flanger punches a hole, including the frame, locate punch a hole mechanism and preceding stack pallet in this frame, its characterized in that: the needle that dashes of oval cross section is installed to the mechanism's work end that punches a hole, still be equipped with external mold clamp splice, mold core, back stack pallet, hollow mold core connecting rod, awl tongue pole connecting rod, mold core connecting rod fixing base and turn -ups driving oil cylinder in the frame in proper order, the mold core includes the outer mold core of hollow, inlays the mold core at outer mold core top is inserted, is located respectively the turn -ups drift and the awl tongue pole in external mold in -core chamber, the turn -ups punch sleeve establish on the awl tongue pole, awl tongue pole is connected to turn -ups driving oil cylinder through awl tongue pole connecting rod, and promote the turn -ups drift and carry out hole flanging processing through removing awl tongue pole, the utility model discloses the process is few, the hole flanging is efficient, abrasion of the die is little, durable, processing cost low, can process the heavy -walled tubular product of thin wall, can be to not equidirectional processing of same pipe fitting.