The embodiment of the invention discloses a fire cover assembly which comprises an outer fire cover, an inner fire cover and a gas distribution disc. An inner fire cover mounting part is arranged in the middle of the outer fire cover, the inner fire cover is arranged on the inner fire cover mounting part, and an inner ring fire gas inlet channel is arranged in the center of the inner fire cover mounting part. A fire hole surface is arranged on the periphery of the outer fire cover, a connecting surface is arranged between the fire hole surface and the inner fire cover mounting part, the outerfire cover is coaxially coupled above the gas distribution disc, and the center of the gas distribution disc is provided with an outer ring fire gas inlet channel. An outer fire cover gas distributionbin is formed between the outer fire cover and the gas distribution plate below the fire hole surface, and a plurality of secondary air inlet channels penetrating through the connecting surface and the gas distribution disc are uniformly distributed on the connecting surface. Since the outer ring fire gas inlet channel is arranged in the center of the gas distribution disc, gas of the outer ringfire gas inlet channel can be uniformly diffused to the outer fire cover gas distribution bin, and then is uniformly distributed to each fire hole for full combustion, and therefore the combustion efficiency is improved.