Waterproof fixing mechanism special for steel structure roof tiles

The utility model discloses a waterproof fixing mechanism special for steel structure roof tiles. The device comprises a purline, a screw, a pressing piece, a sealing film and a waterproof cap, steelstructure roof tiles of which the edges are stacked together are placed on the purlines; a sealing film is placed at the wave crest position of the edge wave longitudinal lap joint area; the pressingpiece presses the sealing film; a screw sequentially penetrates through the pressing piece, the sealing rubber piece, the steel structure roof tile edge wave longitudinal lap joint area and the purline from the top of the pressing piece to bottom. The screw is finally screwed and fastened with the purline in a screw-thread fit manner; an extension ring is upwards formed at the top of the pressingpiece and is positioned at the periphery of the screw cap head; threads are formed on the outer wall of the extension ring, correspondingly, threads are also formed on the inner wall of the waterproofcap, the waterproof cap is