The utility model relates to a magnetic field shielding device for a dry-type hollow smoothing reactor. The protection device comprises a protection plate which is arranged under the dry-type hollow smoothing reactor and is parallel to the bottom surface of the dry-type hollow smoothing reactor, the area of the protection plate is larger than that of the bottom surface of the dry-type hollow smoothing reactor, and the protection plate is made of a magnetic conductive material. Through the design of the protective fence, the shielding effect of the fence on a magnetic field is improved, electromagnetic pollution near the ground of a converter station is reduced, and the magnetic field intensity near a safety passage is remarkably reduced. According to the utility model, the problem of overlarge electromagnetic pollution of the converter station exit passageway is solved, and workers are prevented from receiving more electromagnetic radiation.