The invention relates to a steel sound proof door which is extensively used for occasions where noise needs to be controlled, such as a studio, a theater, a broadcasting studio, a recording studio, a cinema, a sound damping chamber, an audiometric room, a machinery room, a sound proof cover and the like. A door leaf is arranged on a door frame through a swing-up type hinge, the door frame is welded on an embedded part of a door opening, cement mortar is poured into a gap between the door frame and the door opening, and a built-in type sealing threshold is adopted; the door frame is formed by spot-welding a front frame plate and a rear frame plate, the door leaf is formed by spot-welding a front leaf plate and a rear leaf plate into a whole, no steel structural frame is arranged in the door leaf, sound proof materials, sound absorption materials and damping materials are filled in the door leaf, magnetic sealing strips and sponge sound absorption strips are arranged at an intersected crack between the door frame and the door leaf, and the door frame and the door leaf can be overlapped with a door frame or a door leaf with a same structure to form the sound proof door with higher sound proof factor. The steel sound proof door has the advantages of reasonable structure, hermetical seal, easy opening and closing, attractive appearance, no cracking and no lower threshold; and the sound proof factor can be divided into a plurality of levels from 35 db to 55 db.