Heat-preservation and fireproof external wall board for ultra-low-energy-consumption building and construction method of external wall board

The invention discloses a heat-preservation and fireproof external wall board for an ultra-low-energy-consumption building and a construction method of the heat-preservation and fireproof external wall board, and relates to the field of building external wall structures. The construction method comprises the following steps that 1, an aerated concrete board is installed, the aerated concrete wall board serves as a main stress structure to be installed, and all gaps of the aerated concrete board are sealed with adhesives and then sealed with waterproof gas insulation films and waterproof gas-permeable films; 2, a foamed ceramic concrete board is installed indoors; and 3, rock wool is pasted outdoors, and hanging net plastering is carried out to protect the rock wool. According to the invention, the thickness of the outdoor rock wool is reduced by increasing the indoor foamed ceramic insulation board, the safety degree of an external envelope system of the ultra-low-energy-consumption building is increased, the