The reason why the coated steel plate can be fireproof and moisture-proof is mainly because its surface is covered with a layer of flame-retardant and moisture-proof membrane material. This membrane material has good waterproof and moisture-proof properties and can effectively isolate the erosion of external moisture and water. At the same time, the steel plate itself has high fire resistance and can resist the burning and spread of flames for a certain period of time, thereby protecting the building structure from the impact of fire.