The invention relates to the technical field of hardware parts, and discloses an automatic sealing device for a hardware part packaging bag. The automatic sealing device for the hardware part packaging bag comprises a base, supporting legs are movably connected to the upper end of the base, a conveying belt is movably connected to the upper ends of the supporting legs, a trigger device is movably connected to the lower portion of the conveying belt, a frame body is movably connected to the upper end of the base, an electromagnet is movably connected to the interior of the frame body, a pull rod is connected to the interior of the frame body in a sleeved mode, a sliding key is movably connected to the exterior of the pull rod, a rotating wheel is movably connected to the exterior of the sliding key, a cam structure is movably connected to the exterior of the sliding key, a drawing rod is movably connected to the exterior of a hinge rod, clamping plates are fixedly connected to the outer portions of the drawing rods, meshing wheels are movably connected to the interiors of the clamping plates, and heating pipes are movably connected to the interiors of the meshing wheels. The automatic sealing device for the hardware part packaging bag has the advantages that the packaging bags can be automatically sealed, manual operation is omitted, therefore working efficiency is improved, and workers are prevented from being scalded.