The invention discloses a fireproofing device for storage buildings. The fireproofing device comprises a fixed cylinder, a direct current pipe is installed in the fixed cylinder, two arc-shaped lateral flow channels are arranged between the direct current pipe and the inner wall of the fixed cylinder, a direct current water channel is arranged in the direct current pipe, the top of the direct current pipe is provided with a current limiting cap which protrudes upward from the top, the current limiting cap is composed of a plurality of current limiting pieces annularly distributed on the top end face of the direct current pipe, the thicknesses of the current limiting plates are progressively increased from the top end to the upper end surface of the direct current pipe, the tail end of the direct current water channel is provided with a plurality of spiral raised parts and a splash box is rotatably arranged on the outer wall of the extending end of the direct current pipe. The fireproofing devices can be combined and respectively mounted on the side wall of a storage rack and the bottom of a beam to cover multiple or single oil drums along all directions. If the storage rack is on fire, fire fighting water is sprayed to the oil drum immediately through the direct current water channel and the lateral flow channels so that spraying blind spots of the oil drum are avoided and oil drum safe storage is ensured.