The invention relates to the technical field of hot-rolled alloy steel drilling devices, in particular to a drilling device for hot-rolled alloy steel HRB500E machining. The defects that during steel bar drilling, fixing is not firm, hole position deviation is caused by fixing deviation, and the drilling position cannot be rapidly designated are solved. The drilling device comprises a base, a stand column and mounting seats are welded to the upper surface of the base, the upper end of the stand column is sleeved with a mounting frame, a first guide rod is welded to the upper surface of the stand column, the surface of the first guide rod is sleeved with a first spring, a drill floor is mounted at one end of the mounting frame, a drill bit is clamped to the bottom of the drill floor, connecting plates are welded to the two sides of the drill floor, second guide rods are clamped in the connecting plates, the surface of each second guide rod is sleeved with a second spring, a clamping plate is welded to the bottom of each second guide rod, a cover plate is clamped to the upper surface of each mounting seat, and a limiting plate is clamped to one side of the base. According to the device, steel bars needing to be machined can be effectively fixed, a center judging device is additionally arranged to guarantee that the clamping position is accurate, and punching deviation is effectively avoided.