The utility model discloses a special split type metal wire box for a garage roof. Wire box comprising a wire box body, the wire box body comprises a lower box body pre-buried in a top plate bottom steel bar. The edge of an upper opening of the lower box body is turned outwards to form a first outer lap joint edge, the first outer lap joint edge is movably connected with an upper box body with a bottom opening in a lap joint mode, the edge of the bottom opening of the upper box body is turned inwards to form an inner lap joint edge matched with the first outer lap joint edge, and the inner lapjoint edge and the first outer lap joint edge are bonded into a whole through adhesives. A knock-off hole is formed in each side wall of the upper box body, and a circular sealing piece is movably inserted into each knock-off hole. The utility model has the advantages of simple structure, split structure, good construction stability and simple construction, shortens the construction period, and is especially suitable for pre-burying the electrical pipeline on the garage roof.